Section 43 of Principles of Geology. This is a LibriVox recording. A LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org, recording by Dion Giants, Salt Lake City, Utah. Principles of Geology by Charles Lyle, Chapter 19, Destroying and transporting effects of tides and currents. Difference in the rise of tides. Legulas and gulf currents. Velocity of currents. Causes of currents. Action of the sea on the British coast. Shetland Islands. Large blocks removed. Isles reduced to clusters of rocks. Orkney Isles. Waste of East Coast of Scotland. Waste of the cliffs of Holderness, Norfolk and Suffolk. Sand dunes, how far chronometers. Silting up of estuaries. Yarmouth Estuary. Suffolk Coast. Dunwich. Essex Coast. Estuary of the Thames. Goodwin Sands. Coast of Kent. Formation of the Straits of Dover. South Coast. Of England. Essex. Hans. Dorset. Portland. Origin of the Chessel Bank. Cornwall. Coast of Brittany. Although the movements of great bodies of water, termed tides and currents, are in general, due to very distinct causes, their effects cannot be studied separately, for they produce by their joint action, aided by that of the waves, those changes which are objects of geological interest. These forces may be viewed in the same manner as we before considered rivers, first as employed in destroying portions of the solid crust of the earth, and removing them to other places, secondly, as reproductive of new strata. Tides. Bees superfluous at the present day to offer any remarks on the cause of the tides. They are not perceptible in lakes or in most inland seas, in the Mediterranean even, deep and extensive as is that sea. They are scarcely sensible to ordinary observation, their effects being quite subordinate to those of the winds and currents. In some places, however, as in the Straits of Messina, there is an ab and flow to the amount of two feet and upwards at Naples, and at the Euripus of twelve or thirteen inches, and at Venice according to Ronell of five feet. In the Cirtus, also of the ancients, two wide shallow gulfs, which penetrate very far within the northern coast of Africa, between Carthage and Cyrene. The rise is said to exceed five feet. In islands remote from any continent, the ab and flow of the ocean is very slight, as at St. Helena, for example, where it is rarely above three feet. In any given line of coast, the tides are greatest in narrow channels, bays and estuaries, and leased in the intervening tracks where the land is prominent. Thus at the entrance of the estuary of the Thames and Medway, the rise of the spring tides is eighteen feet. But when we follow our eastern coast from Thence northward towards Lowstaff and Yarmouth, we find a gradual diminution until at the places last mentioned, the highest rise is only seven or eight feet. From this point, there begins again to be an increase, so that at Cormor, where the coast again retires towards the west, the rise is sixteen feet. And towards the extremity of the gulf called the Wash, as at Lin and in Boston Deeps, it is from twenty-two to twenty-four feet. And in some extraordinary cases, twenty-six feet. From Thence again, there is a decrease towards the north, the elevation at the Spurn Point being from nineteen to twenty feet, and at Flamborough Head and the Yorkshire coast from fourteen to sixteen feet. At Milford Haven in Pembrokeshire, at the mouth of the Bristol Channel, the tides rise thirty-six feet, and at King Road, near Bristol, forty-two feet. At Chepstow on the Y, a small river which opens into the estuary of the Severn, they reach fifty feet, and sometimes sixty-nine, and even seventy-two feet. A current which sets in on the French coast to the west of Cape La Hague comes pent up by Guernsey, Jersey and other islands, till the rise of the tide is from twenty to forty-five feet, which last height it attains at Jersey. And at St. Molo, a seaport of Brittany, the tides in the basin of mines at the head of the Bay of Fundy in Nova Scotia rise to the height of seventy feet. There are, however, some coasts where the tides seem to offer an exception to the rule above mentioned. For while there is scarcely any rise in the estuary of the Plata in South America, there is an extremely high tide on the open coast of Patagonia, farther to the south. Yet even in this region, the tides reach their greatest elevation, about fifty feet, in the straits of Magellan, and so far, at least, they conform to the general rule. Currents, the most extensive and best determined system of currents, is that which has its source in the Indian Ocean under the influence of the trade winds, and which, after doubling the Cape of Good Hope, inclines to the northward along the western coast of Africa, and then across the Atlantic, near the equator, where it is called the Equatorial Current, and is lost in the Caribbean Sea, yet seems to be again revived in the current, which issues from the Gulf of Mexico. From thence it flows rapidly through the straits of Bahama, taking the name of the Gulf Stream, and passing in a northeasterly direction by the banks of Newfoundland towards the Azores. We learn from the posthumous work of Rennell on this subject that the Lagoolas current, so called from the Cape and Bank of that name, is formed by the junction of two streams flowing from the Indian Ocean, the one from the Channel of Mozambique, down the southeast coast of Africa, the other from the ocean at large. The collective stream is from 90 to 100 miles in breadth, and runs at the rate of from two and a half to more than four miles per hour. It is at length, turned westward by the Lagoolas Bank, which rises from a sea of great doubt to within 100 fathoms of the surface. It must therefore be inferred, says Rennell, that the current here is more than 100 fathoms deep, otherwise the main body of it would pass across the bank instead of being deflected westward, so as to flow round the Cape of Good Hope. From this Cape it flows northward, as before stated, along the western coast of Africa, taking the name of the South Atlantic Current. It then enters the Bight or Bay of Benin, and is turned westward partly by the form of the coast there, and partly perhaps by the Guinea Current, which runs from the north into the same Great Bay. From the center of this bay proceeds the equatorial current, already mentioned, holding a westerly direction across the Atlantic, which it traverses from the coast of Guinea to that of Brazil, flowing afterwards by the shores of Guiana to the west Indies. The breadth of this current varies from 160 to 450 geographical miles, and its velocity is from 25 to 79 miles per day, the mean rate being about 30 miles. The length of its whole course is about 4,000 miles. As it skirts the coast of Guiana, it is increased by the influx of the waters of the Amazon and Orinoco, and by their junction acquires accelerated velocity. After passing the island of Trinidad, it expands and is almost lost in the Caribbean Sea, but there appears to be a general movement of that sea towards the Mexican Gulf, which discharges the most powerful of all currents through the Straits of Florida, where the waters run in the northern part with a velocity of four or five miles an hour, having a breadth from 35 to 50 miles. The temperature of the Gulf of Mexico is 86 degrees Fahrenheit in the summer, or six degrees higher than that of the ocean, in the same parallel, 25 degrees north latitude, and a large proportion of this warmth is retained, even where the stream reaches the 43 degree north latitude. After issuing from the Straits of Florida, the current runs in a northerly direction to Cape Hatteras in North Carolina, about 35 degrees north latitude, where it is more than 70 miles broad, and still moves at the rate of 75 miles per day. In about the 40 degree north latitude, it is turned more towards the Atlantic by the extensive banks of Nantucket and St. George, which are from 200 to 300 feet beneath the surface of the sea, a clear proof that the current exceeds that depth. On arriving near the Azores, the stream widens and overflows as it were, forming a large expanse of warm water in the center of the North Atlantic, over a space of 200 or 300 miles from north to south, and having a temperature of from eight degrees to 10 degrees Fahrenheit above the surrounding ocean. The whole area covered by the Gulf water is estimated by rental at 2,000 miles in length and at a mean 350 miles in breadth, an area more extensive than that of the Mediterranean. The warm water has been sometimes known to reach the Bay of Biscay, still retaining five degrees of temperature above that of the adjoining ocean, and a branch of the Gulf current occasionally drifts fruits, plants, and wood, the produce of America and the West Indies to the shores of Ireland and the Hebrides. From the above statements, we may understand why Rennell has characterized some of the principal currents as oceanic rivers, which he describes as being from 50 to 250 miles in breadth, and having a rapidity exceeding that of the largest navigable rivers of the continents and so deep as to be sometimes obstructed and occasionally turned aside by bank, the tops of which do not rise within 40, 50, or even 100 fathoms of the surface of the sea. Greatest velocity of currents. The ordinary velocity of the principal currents of the ocean is from one to three miles per hour, but when the boundary lands converge, large bodies of water are driven gradually into a narrow space and then wanting lateral room are compelled to raise their level. Whenever this occurs, their velocity is much increased. The current, which runs through the race of Alderney between the island of that name and the mainland, has a velocity of about eight English miles an hour. Captain Hewitt found that in the Pentland Firth, the stream in ordinary spring tides runs 10 miles and a half an hour and about 13 miles during violent storms. The greatest velocity of the tidal current through the Shoots or New Passage in the Bristol Channel is 14 English miles an hour and Captain King observed in his survey of the Straits of Magellan that the tide ran at the same rate through the first narrows and about eight geographical miles an hour in other parts of those straits, causes of currents that movements of no inconsiderable magnitude should be impressed on an expansive ocean by winds blowing for many months in one direction may easily be conceived when we observe the effects produced in our own seas by the temporary action of the same cause. It is well known that a strong southwest or northwest wind invariably raises the tides to an unusual height along the west coast of England and in the Channel and that a northwest wind of any continuance causes the Baltic to rise two feet and upwards above its ordinary level. Smeaton ascertained by experiment that in a canal four miles in length the water was kept up four inches higher at one end than at the other merely by the action of the wind along the canal and Reynolds informs us that a large piece of water ten miles broad and generally only three feet deep has by a strong wind had its waters driven to one side and sustained so as to become six feet deep while the windward side was laid dry as water therefore he observes when pent up so that it cannot escape acquires a higher level so in a place where it can escape the same operation produces a current and this current will extend to a greater or less distance according to the force by which it is produced by the side of the principal oceanic currents such as the legulas and the Gulf Stream are parallel counter currents running steadily in an opposite direction currents flowing alternately in opposite directions are occasioned by the rise and fall of the tides the effect of this cause is as before observed most striking in estuaries and channels between islands a third cause of oceanic currents is evaporation by solar heat of which the great current setting through the straits of Gibraltar into the Mediterranean is a remarkable example and will be fully considered in the next chapter a stream of colder water also flows from the black sea into the Mediterranean it must happen in many other parts of the world that large quantities of water raised from one tract of the ocean by solar heat are carried to some other where the vapor is condensed and falls in the shape of rain and this in flowing back again to restore equilibrium will cause sensible currents these considerations naturally lead to the inquiry whether the level of those seas out of which currents flow is higher than that of seas into which they flow if not the effect must be immediately equalized by undercurrents or counter currents are ago is of opinion that so far as observations have gone there are no exact proofs of any such difference of level it was inferred from the measurements of Missour La Perre that the level of the Mediterranean near Alexandria was lower by 26 feet six inches than the Red Sea near Suez at low water and about 30 feet lower than the Red Sea at the same place at high water but Mr. Robert Stevenson affirms as the result of a more recent survey that there is no difference of level between the two seas it was formerly imagined that there was an equal if not greater diversity in the relative levels of the Atlantic and Pacific on the opposite sides of the isthmus of Panama but the levelings carried across that isthmus by Captain Lloyd in 1828 to ascertain the relative height of the Pacific Ocean at Panama and of the Atlantic at the mouth of the River Chagras have shown that the difference of mean level between those oceans is not considerable and contrary to expectation the difference which does exist is in favor of the greater height of the Pacific according to this survey the mean height of the Pacific is three feet and a half or 3.52 above the Atlantic if we assume the mean level of a sea to coincide with the mean between the extremes of the elevation and depression of the tides for between the extreme levels of the greatest tides in the Pacific at Panama there is a difference of 27.44 feet and at the usual spring tides 21.22 feet whereas at Chagras this difference is only 1.16 feet and is the same at all seasons of the year the tides in short in the Caribbean Sea are scarcely perceptible not equaling those in some parts of the Mediterranean whereas the rise is very high in the Bay of Panama so that the Pacific is at high tide lifted up several feet above the surface of the Gulf of Mexico and then at low water let down as far below it but astronomers are agreed that on mathematical principles the rise of the tidal wave above the mean level of a particular sea must be greater than the fall below it and although the difference has been hitherto supposed insufficient to cause an appreciable error it is nevertheless worthy of observation that the error such as it may be would tend to reduce the small difference now inferred from the observations of Mr. Lloyd to exist between the levels of the two oceans there is still another way in which heat and cold must occasion great movements in the ocean a cause to which perhaps currents are principally due whenever the temperature of the surface of the sea is lowered condensation takes place and the superficial water having its specific gravity increased falls to the bottom upon which lighter water rises immediately and occupies its place when this circulation of ascending and descending currents has gone on for a certain time in high latitudes the inferior parts of the sea are made to consist of colder or heavier fluid than the corresponding depths of the ocean between the tropics if there be a free communication if no chain of submarine mountains divide the polar from the equatorial basins a horizontal movement will arise by the flowing of colder water from the poles to the equator and there will then be a reflux of warmer superficial water from the equator to the poles a well-known experiment has been induced to elucidate this mode of action in explanation of the trade winds if a long trough divided in the middle by a sluice or partition have one end filled with water and the other with quicksilver both fluids will remain quiet so long as they are divided but when the sluice is drawn up the heavier fluid will rush along the bottom of the trough while the lighter being displaced will rise and flowing in an opposite direction spread itself at the top in like manner the expansion and contraction of seawater by heat and cold have a tendency to set undercurrents in motion from the poles to the equator and to cause countercurrents at the surface which are impelled in a direction contrary to that of the prevailing trade winds the geographical and other circumstances being very complicated we cannot expect to trace separately the movements due to each cause but must be prepared for many anomalies especially as the configuration of the bed of the ocean must often modify and interfere with the course of the inferior currents as much as the position and form of continents and islands alter the direction of those on the surface thus on sounding at great depths in the Mediterranean captains barard and derville have found that the cold does not increase in a high ratio as in the tropical regions of the ocean the thermometer remaining fixed at about 55 degrees Fahrenheit between the depths of 1,000 and 6,000 feet this might have been anticipated as captain smith in his survey had shown that the deepest part of the straits of Gibraltar is only 1,320 feet so that a submarine barrier exists there which must prevent the influx of any undercurrent of the ocean cooled by polar ice each of the four causes above mentioned the wind the tides evaporation and the expansion and contraction of water by heat and cold may be conceived to operate independently of the others and although the influence of all the rest were annihilated but there is another cause the rotation of the earth on its axis which can only come into play when the waters have already been set in motion by someone or all of the forces above described and when the direction of the current so raised happens to be from south to north or from north to south the principle on which this cause operates is probably familiar to the reader as it has long been recognized in the case of the trade winds without enlarging therefore on the theory it will be sufficient to offer an example of the mode of action alluded to when a current flows from the Cape of Good Hope towards the Gulf of Guinea it consists of a mass of water which on doubling the Cape in latitude 35 degrees has a rotatory velocity of about 800 miles an hour but when it reaches the line where it turns westward it has arrived at a parallel where the surface of the earth is whirled round at the rate of 1000 miles an hour or about 200 miles faster if this great mass of water was transferred suddenly from the higher to the lower latitude the deficiency of its rotatory motion relatively to the land and water with which it would come into juxtaposition would be such as to cause an apparent motion of the most rapid kind of no less than 200 miles an hour from east to west in the case of such a sudden transfer the eastern coast of america being carried round in an opposite direction might strike against a large body of water with tremendous violence and a considerable part of the continent might be submerged this disturbance does not occur because the water of the stream as it advances gradually into new zones of the sea which are moving more rapidly acquires by friction and accelerated velocity yet as this motion is not imparted instantaneously the fluid is unable to keep up with the full speed of the new surface over which it is successively brought hence to borrow the language of Herschel when he speaks of the trade winds it lags or hangs back in a direction opposite to the earth's rotation that is from east to west and thus a current which would have run simply towards the north but for the rotation may acquire a relative direction towards the west we may next consider a case where the circumstances are the converse of the above the gulf stream flowing from about latitude 20 degrees is at first impressed with a velocity of rotation of about 940 miles an hour and runs to the latitude 40 degrees where the earth revolves only at the rate of 766 miles or 174 miles slower in this case a relative motion of an opposite kind may result and the current may retain an excess of rotatory velocity tending continually to deflect it westward polar currents therefore or those flowing from high to low latitudes are driven towards the eastern shores of continents while tropical currents flowing towards the poles are directed against their western shores thus it will be seen that currents depend like the tides on no temporary or accidental circumstances but on the laws which preside over the motions of the heavenly bodies but although the sum of their influence in altering the surface of the earth may be very constant throughout successive epochs yet the points where these operations are displayed in fullest energy shift perpetually the height to which the tides rise and the violence and velocity of currents depend in a great measure on the actual configuration of the land the contour of a long line of continental or insular coast the depth and breadth of channels the peculiar form of the bottom of seas in a word on a combination of circumstances which are made to vary continually by many igneous and aqueous causes and amongst the rest by the tides and currents themselves although these agents therefore of decay and reproduction are local in reference to periods of short duration such as those which history embraces they are nevertheless universal if we extend our views to a sufficient lapse of ages end of chapter 19 part 1 section 44 of principles of geology this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org recording by Dion Giants Salt Lake City Utah principles of geology by Charles Lyle chapter 19 part 2 destroying and transporting power of currents after these preliminary remarks on the nature and causes of currents their velocity and direction we may next consider their action on the solid materials of the earth we shall find that their efforts are in many respects strictly analogous to those of rivers I have already treated in the third chapter of the manner in which currents sometimes combine with ice in carrying mud pebbles and large fragments of rock to great distances their operations are more concealed from our view than those of rivers but extend over wider areas and are therefore of more geological importance waste of the British coasts Shetland Islands if we follow the eastern and southern shores of the British islands from our Ultima Thule in Shetland to the lands end in Cornwall we shall find evidence of a series of changes since the historical era very illustrative of the kind and degree of force exerted by tides and currents cooperating with the waves of the sea in this survey we shall have an opportunity of tracing their joint power on islands promontories bays and estuaries on bold lofty cliffs as well as on low shores and on every description of rock and soil from granite to blown sand the northernmost group of the British islands the Shetland are composed of a great variety of rocks including granite, niece, mica slate, serpentine, greenstone and many others with some secondary rocks chiefly sandstone and conglomerate these islands are exposed continually to the uncontrolled violence of the Atlantic for no land intervenes between their western shores and America the prevalence therefore of strong westerly gales causes the waves to be sometimes driven with irresistible force upon the coast while there is also a current setting from the north the spray of the sea aids the decomposition of the rocks and prepares them to be breached by the mechanical force of the waves steep cliffs are hollowed out into deep caves and lofty arches and almost every promontory ends in a cluster of rocks imitating the forms of columns, pinnacles and obelisks drifting of large masses of rock modern observations show that the reduction of continuous tracts to such insular masses is a process in which nature is still actively engaged the isle of stendness says dr. hibbert presents a scene of unequal desolation in stormy winters huge blocks of stone are overturned or are removed from their native beds and hurried up a slight eclivity to a distance almost incredible in the winter of 1802 a tabular shaped mass eight feet two inches by seven feet and five feet one inch thick was dislodged from its bed and removed to a distance of from 80 to 90 feet i measured the recent bed from which a block had been carried away the preceding winter ad 18 18 and found it to be 17 feet and a half by seven feet and the depth two feet eight inches the removed mass had been born to a distance of 30 feet when it was shivered into 13 or more lesser fragments some of which were carried still farther from 30 to 120 feet a block nine feet two inches by six feet and a half and four feet thick was hurried up the eclivity to a distance of 150 feet at north maven also angular blocks of stone have been removed in a similar manner to considerable distances by the waves of the sea some of which are represented in the annexed figure effects of lightning in addition to numerous examples of masses detached and driven by the waves tides and currents from their plays some remarkable effects of lightning are recorded in these aisles at funsy in fetlar about the middle of the last century a rock of mica schist 105 feet long 10 feet broad and in some places four feet thick was in an instant torn by a flash of lightning from its bed and broken into three large and several smaller fragments one of these 26 feet long 10 feet broad and four feet thick was simply turned over the second which was 28 feet long 17 broad and five feet in thickness was hurled across a high point to the distance of 50 yards another broken mass about 40 feet long was thrown still farther but in the same direction quite into the sea there were also many smaller fragments scattered up and down when we thus see electricity cooperating with the violent movements of the ocean in heaping up piles of shattered rock on dry land and beneath the waters we cannot but admit that a region which shall be the theater for myriads of ages of the action of such disturbing causes might present at some future period if upraised far above the bosom of the deep a scene of havoc and ruin that may compare with any now found by the geologist on the surface of our continents in some of the shetland aisles as on the west of michael row dykes or veins of soft granite have molded away while the matrix in which they were enclosed being of the same substance but of a firmer texture has remained unaltered thus long narrow ravines sometimes 20 feet wide are laid open and often give access to the waves after describing some huge cavernous apertures into which the sea flows for 250 feet in ronus dr. hibbert writing in 1822 enumerates other ravages of the ocean a mass of rock the average dimensions of which may perhaps be rated at 12 or 13 feet square and four and a half or five in thickness was first moved from its bed about 50 years ago to a distance of 30 feet and has since been twice turned over passage forced by the sea through porphyritic rocks but the most sublime scene is where a mural pile of porphyry escaping the process of disintegration that is devastating the coast appears to have been left as a sort of rampart against the inroads of the ocean the atlantic when provoked by wintery gales batters against it with all the force of real artillery the waves having in their repeated assaults forced themselves an entrance this breach named the grind of the navier is widened every winter by the overwhelming surge that finding a passage through it separates large stones from its sides and forces them to a distance of no less than 180 feet in two or three spots the fragments which have been detached are brought together in immense heaps that appear as an accumulation of cubicle masses the product of some quarry it is evident from this example that although the greater indestructibility of some rocks may enable them to withstand for a longer time the action of the elements yet they cannot permanently resist there are localities in shetland in which rocks of almost every variety of mineral composition are suffering disintegration thus the sea makes great inroads on the clay slate of fitful head on the serpentine of the vaude hill in fitler and on the mica schist of the bay of triesta on the east coast of the same island which decomposes into angular blocks the quartz rock on the east of walls and the nice and mica schist of garthness suffer the same fate destruction of islands such devastation cannot be incessantly committed for thousands of years without dividing islands until they become at last mere clusters of rocks the last shreds of masses once continuous to this state many appear to have been reduced and innumerable fantastic forms are assumed by rocks adjoining these islands to which the name of drongs is applied as it is to those of similar shape in ferro the granite rocks between papa stour and hillswick nests afford an example as still more singular cluster of rocks is seen to the south of hillswick nests which presents a variety of forms as viewed from different points and has often been likened to a small fleet of vessels with spread sails we may imagine that in the course of time hillswick nests itself may present a similar wreck from the unequal decomposition of the rocks whereof it is composed consisting of nice and mica schist traversed in all directions by veins of feldspar porphyry midway between the groups of shetland and orkney is fair island said to be composed of sandstone with high perpendicular cliffs the current runs with such velocity that during a calm and when there is no swell the rocks on its shores are white with the foam of the sea driven against them the orkneys if carefully examined would probably illustrate our present topic as much as the shetland group the northeast promontory of sanda one of these islands has been cut off in modern times by the sea so that it became what is now called start island where a lighthouse was erected in 1807 since which time the new straight has grown broader east coast of scotland to pass over to the mainland of scotland we find that in invernus shire there have been inroads of the sea at fort george and others in moresure which have swept away the old town of findhorn on the coast of kincardenshire an illustration was afforded at the close of the last century of the effect of promontories in protecting a line of low shore the village of mathors two miles south of johnshaven was built on an ancient shingle beach protected by a projecting ledge of limestone rock this was quarried for lime to such an extent that the sea broke and in 1795 carried away the whole village in one night and penetrated 150 yards inland where it has maintained its ground ever since the new village having been built farther inland on the new shore in the bay of montrose we find the north esc and the south esc rivers pouring annually into the sea large quantities of sand and pebbles yet they have formed no deltas for the waves aided by the current setting across their mouths sweep away all the materials considerable beds of shingle brought down by the north esc are seen along the beach proceeding southwards we learned that at our booth in fortesure which stands on a rock of red sandstone gardens and houses have been carried away since the commencement of the present century by encroachments of the sea it had become necessary before 1828 to remove the lighthouses at the mouth of the estuary of the tay in the same county at buttoness which were built on a tract of blown sand the sea having encroached for three quarters of a mile forces of waves and currents in estuaries the combined power which waves and currents can exert in estuaries a term which i can find to bays entered both by rivers and the tides of the sea was remarkably exhibited during the building of the bell rock lighthouse off the mouth of the tay the bell rock is a sunken reef consisting of red sandstone being from 12 to 16 feet under the surface at high water and about 12 miles from the mainland at the distance of 100 yards there is a depth in all directions of two or three fathoms at low water in 1807 during the erection of the lighthouse six large blocks of granite which had been landed on the reef were removed by the force of the sea and thrown over a rising ledge to the distance of 12 or 15 paces and an anchor weighing about 2200 weight was thrown up upon the rock mr stevensson informs us moreover that driftstones measuring upwards of 30 cubic feet or more than two tons weight have during storms been often thrown upon the rock from the deep water submarine forest among the proof that the sea has encroached on the land bordering the estuary of the tay dr fleming has mentioned a submarine forest which has been traced for several miles along the northern shore of the county of fife but subsequent surveys seem to have shown that the bed of peat containing tree roots leaves and branches now occurring at a lower level than the tay must have come into its present position by a general sinking of the ground on which the forest grew the peat bed alluded to is not confined says dr buest to the present channel of the tay but extends far beyond it and is covered by stratified clay from 15 to 25 feet in thickness in the mists of which in some places is a bed full of seashells recent discoveries having established the fact that upward and downward movements have affected our island since the general coastline had nearly acquired its present shape we must hesitate before we attribute any given change to a single cause such as the local encroachment of the sea upon low land on the coast of fife at st andrew's attractive land said to have intervened between the castle of cardinal beaten and the sea has been entirely swept away as were the last remains of the priory of creole in the same county in 1803 on both sides of the frith of fourth land has been consumed at north berwick in particular and at new haven where an arsenal and dock built in the reign of james the fourth in the 15th century has been overflowed east coast of england if we now proceed to the English coast we find records of numerous lands having been destroyed in northumberland as those near bamboo and holy island and at time mouth castle which now overhangs the sea although formerly separated from it by a strip of land at hardle pool and several other parts of the coast of durham composed of magnesium limestone the sea has made considerable inroads coast of yorkshire almost the whole coast of yorkshire from the mouth of the teas to that of the humber is in a state of gradual dilapidation that part of the cliffs which consist of lias the old light series and chalk decays slowly they present abrupt and naked precipices often 300 feet in height and it is only at a few points that the grassy covering of the sloping talus marks a temporary relaxation of the erosive action of the sea the chalk cliffs are worn into caves and needles in the projecting headland of flamborough where they are decomposed by the salt spray and slowly crumble away but the waste is most rapid between that promontory and spurn point or the coast of holderness as it is called attract consisting of beds of clay gravel sand and chalk rubble the irregular intermixture of the argillaceous beds causes many springs to be thrown out and this facilitates the undermining process the waves beating against them and a strong current setting chiefly from the north the wasteful action is very conspicuous at dimlington height the loftiest point in holderness where the beacon stands on a cliff 146 feet above high water the whole being composed of clay with pebbles scattered through it for many years says professor phillips the rate at which the cliffs recede from bridlington to spurn a distance of 36 miles has been found by measurement to equal on an average two and a quarter yards annually which upon 36 miles of coast would amount to about 30 acres a year at this rate the coast the mean height of which above the sea is about 40 feet has lost one mile in breadth since the norman conquest and more than two miles since the occupation of york eboracum by the romans the extent of this denudation as estimated by the number of cubic feet of matter removed annually will be again spoken of in chapter 22 in the old maps of york we find spots now sandbanks in the sea marked as the ancient sites of the towns and villages of auburn heartburn and hide of hide says pennant only the tradition is left and near the village of hornsea a street called hornsea back has long since been swallowed althorn and its church have also been in great part destroyed and the village of kilts knee but these places are now removed farther inland the annual rate of encroachment at althorn for several years preceding 1830 is stated to have averaged about four yards not unreasonable fears are entertained that at some future time the spurn point will become an island and that the ocean entering into the estuary of the humbur will cause great devastation pennant after speaking of the silting up of some ancient ports in that estuary observes but in return the sea has made most ample reprisals the site and even the very names of several places once towns of note upon the humbur are now only recorded in history and raven spur was at one time a rival to hull and a port so very considerable in 1332 that edward bolial and the confederated english barons sailed from hence to invade scotland and henry the fourth in 1399 made choice of this port to land at to affect the deposal of richard the second yet the whole of this has long since been devoured by the merciless ocean extensive sands dry at low water are to be seen in their stead pennant describes spurn head as a promontory in the form of a sickle and says the land for some miles to the north was perpetually preyed on by the fury of the german sea which devours whole acres at a time and exposes on the shores considerable quantities of beautiful amber lincoln sure the maritime district of lincoln sure consists chiefly of lands that lie below the level of the sea being protected by embankments some of the fens were embanked and drained by the romans but after their departure the sea returned and large tracks were covered with beds of silt containing marine shells now again converted into productive lands many dreadful catastrophes are recorded by incursions of the sea whereby several parishes have been at different times overwhelmed end of chapter 19 part 2 section 45 of principles of geology this is a libravox recording all libravox recordings are in the public domain for more information or to volunteer please visit libravox.org recording by dion jones salt lake city utah principles of geology by charles lile chapter 19 part 3 norfolk the decay of the cliffs of norfolk and suffolk is incessant at hunt statin on the north the undermining of the lower erinaceous beds at the foot of the cliff causes masses of red and white chalk to be precipitated from above between hunt statin and wayborne low hills or dunes of blown sand are formed along the shore from fifty to sixty feet high they are composed of dry sand bound in a compact mass by the long creeping roots of the plant called merrum a rondo arania such is the present set of the tides that the harbors of clay wells and other places are securely defended by these barriers affording a clear proof that it is not the strength of the material at particular points that determines whether the sea shall be progressive or stationary but the general contour of the coast the waves constantly undermine the low chalk cliffs covered with sand and clay between wayborne and sharing him a certain portion of them being annually removed at the latter town i ascertained in 1829 some facts which throw light on the rate at which the sea gains upon the land it was computed when the present in was built in 1805 that it would require seventy years for the sea to reach the spot the mean loss of land being calculated from previous observations to be somewhat less than one yard annually the distance between the house and the sea was fifty yards but no allowance was made for the slope of the ground being from the sea in consequence of which the waste was naturally accelerated every year as the cliff grew lower there being at each succeeding period less matter to remove when portions of equal area fell down between the years 1824 and 1829 no less than seventeen yards were swept away and only a small garden was then left between the building and the sea there was in 1829 a depth of twenty feet sufficient to float a frigate at one point in the harbor of that port where only forty eight years before there stood a cliff fifty feet high and houses upon it if once in half a century an equal amount of change were produced suddenly by the momentary shock of an earthquake history would be filled with records of such wonderful revolutions of the earth's surface but if the conversion of high land into deep sea be gradual it excites only local attention the flagstaff of the preventive service station on the south side of this harbor was thrice removed inland between the years 1814 and 1829 in consequence of the advance of the sea farther to the south we find cliffs composed like those of holderness before mentioned of alternating strata of blue clay gravel loam and fine sand although they sometimes exceed 300 feet in height the havoc made on the coast is most formidable the whole site of ancient kromer now forms part of the german ocean the inhabitants having gradually retreated inland to their present situation from whence the sea still threatens to dislodge them in the winter of 1825 a fallen mass was precipitated from near the lighthouse which covered 12 acres extending far into the sea the cliffs being 250 feet in height the undermining by springs has sometimes caused large portions of the upper part of the cliffs with houses still standing upon them to give way so that it is impossible by erecting breakwaters at the base of the cliffs permanently to ward off the danger on the same coast says mr rc taylor the ancient villages of shipton wimpwell and eckles have disappeared several manners and large portions of neighboring parishes having piece after piece been swallowed up nor has there been any intermission from time immemorial in the ravages of the sea along a line of coast 20 miles in length in which these places stood of eckles however a monument still remains in the reigned tower of the old church which is half buried in the dunes of sand within a few paces 60 of the sea beach so early as 1605 the inhabitants petitioned james the first for a reduction of taxes as 300 acres of land and all their houses save 14 had then been destroyed by the sea not one half that number of acres now remains in the parish and hills of blown sand now occupy the site of the houses which were still extant in 1605 when i visited the spot in 1839 the sea was fast encroaching on the sand hills and had laid open on the beach the foundations of a house 14 yard square the upper part of which had evidently been pulled down before it had been buried under sand the body of the church has also been long buried but the tower still remains visible m e de bomont has suggested that sand dunes in holland and other countries may serve as natural chronometers by which the date of the existing continents may be ascertained the sands he says are continually blown inland by the force of the winds and by observing the rate of their march we may calculate the period when the movement commenced but the example just given will satisfy every geologist that we cannot ascertain the starting point of dunes all coasts being liable to waste and the shores of the low countries in particular being not only exposed to inroads of the sea but as mesur de bomont himself has well shown having even in historical times undergone a change of level the dunes may indeed in some cases be made use of as chronometers to enable us to assign a minimum of antiquity to existing coastlines but this test must be applied with great caution so variable is the rate at which the sands may advance into the interior hills of blown sand between eckles and winterton have barred up and excluded the tide for many hundred years from the mouths of several small estuaries but there are records of nine breaches from 20 to 120 yards wide having been made through these by which immense damage was done to the low grounds in the interior a few miles south of hapusburg also are hills of blown sand which extend to yarmouth these dunes afford a temporary protection to the coast and an inland cliff about a mile long at winterton shows clearly that at that point the sea must have penetrated formerly farther than at present silting up of estuaries at yarmouth the sea has not advanced upon the sands in the slightest degree since the reign of elizabeth in the time of the saxons a great estuary extended as far as norwich which city is represented even in the 13th and 14th centuries as situated on the banks of an arm of the sea the sands where on yarmouth is built first became firm and habitable ground about the year 1008 from which time a line of dunes has gradually increased in height and breadth stretching across the whole entrance of the ancient estuary and obstructing the ingress of the tides so completely that they are only admitted by the narrow passage which the river keeps open and which has gradually shifted several miles to the south the ordinary tides at the river's mouth rise at present only to the height of three or four feet the spring tides to about eight or nine by the exclusion of the sea thousands of acres in the interior have become cultivated lands and exclusive of smaller pools upwards of 60 freshwater lakes have been formed varying in depth from 15 to 30 feet and in extent from one acre to 1200 the jar and other rivers frequently communicate with these sheets of water and thus they are liable to be filled up gradually with lacustrine and fluvia tile deposits and to be converted into land covered with forests yet it must not be imagined that the acquisition of new land fit for cultivation in Norfolk and Suffolk indicates any permanent growth of the eastern limits of our island to compensate its reiterated losses no delta can form on such a shore immediately off yarmouth and parallel to the shore is a great range of sand banks the shape of which varies slowly from year to year and often suddenly after great storms captain hewitt rn found in these banks in 1836 a broad channel 65 feet deep where there was only a depth of four feet during a prior survey in 1822 the sea had evacuated to the depth of 60 feet in the course of 14 years or perhaps a shorter period the new channel thus formed serves at present 1838 for the entrance of ships into yarmouth roads and the magnitude of this change shows how easily a new set of the waves and currents might endanger the submergence of the land gained within the ancient estuary of the yard that great bank should be thrown across the mouths of estuaries on our eastern coast where there is not a large body of river water to maintain an open channel is perfectly intelligible when we bear in mind that the marine current sweeping along the coast is charged with the materials of wasting cliffs and ready to form a bar anywhere the instant its course is interrupted or checked by any opposing stream the mouth of the yard has been within the last five centuries diverted about four miles to the south in like manner it is evident that at some remote period the river old entered the sea at old borough until its ancient outlet was barred up and at length transferred to a point no less than 10 miles distant to the southwest in this case ridges of sand and shingle like those of low stoff ness which will be described by and by have been thrown up between the river and the sea and an ancient sea cliff is to be seen now inland it may be asked why the rivers on our east coast are always deflected southwards although the title current flows alternately from the south and north the cause is to be found in the superior force of what is commonly called the flood tide from the north a tidal wave derived from the atlantic a small part of which passes eastward up the english channel and through the straits of dover and then northwards while the principal body of water moving much more rapidly in a more open sea on the western side of britain first passes the orkneys and then turning flows down between norway and scotland and sweeps with great velocity along our eastern coast it is well known that the highest tides on this coast are occasioned by a powerful northwest wind which raises the eastern part of the atlantic and causes it to pour a greater volume of water into the german ocean this circumstance of a violent offshore wind being attended with a rise of the waters instead of a general retreat of the sea naturally excites the wonder of the inhabitants of our coast in many districts they look with confidence for a rich harvest of that valuable manure the seaweed when the north westerly gales prevail and are rarely disappointed coast of suffolk the cliffs of suffolk to which we next proceed are somewhat less elevated than those of norfolk but composed of similar alternations of clay sand and gravel from gorleston in suffolk to within a few miles north of lowstaff the cliffs are slowly undermined near the last mentioned town there is an island cliff about 60 feet high the sloping talus of which is covered with turf and heath between the cliff and the sea is a low flat tract of sand called the nests nearly three miles long and for the most part out of reach of the highest tides the point of the nests projects from the base of the original cliff to the distance of 660 yards this accession of land says mr taylor has been affected at distinct and distant intervals by the influence of currents running between the land and a shoal about a mile off lowstaff called the home sand the lines of growth in the nests are indicated by a series of concentric ridges or embankments in closing limited areas and several of these ridges have been formed within the observation of persons now living a rampart of heavy materials is first thrown up to an unusual altitude by some extraordinary tide attended with a violent gale subsequent tides extend the base of this high bank of shingle and the interstices are then filled with sand blown from the beach the arundo and other marine plants by degrees obtain a footing and creeping along the ridge gives solidity to the mass and form in some cases a matted covering of turf meanwhile another mound is forming externally which by the like process rises and gives protection to the first if the sea forces its way through one of the external and incomplete mounds the breach is soon repaired after a while the marine plants within the areas enclosed by these embankments are succeeded by a better species of urbage affording good pasture edge and the sands become sufficiently firm to support buildings destruction of dunwich by the sea of the gradual destruction of dunwich once the most considerable seaport on this coast we have many authentic records gardener in his history of that borough published in 1754 shows by reference to documents beginning with doomsday book that the cliffs at dunwich south walled eastern and pakefield have been always subject to wear away at dunwich in particular two treks of land which had been taxed in the 11th century in the time of king edward the confessor are mentioned in the conqueror's survey made but a few years afterwards as having been devoured by the sea the losses at a subsequent period of a monastery at another of several churches afterwards of the old port then of 400 houses at once of the church at saint lenard the high road town hall jail and many other buildings are mentioned with the dates when they perished it is stated that in the 16th century not one quarter of the town was left standing yet the inhabitants retreating inland the name was preserved as has been the case with many other ports when their ancient site has been blotted out there is however a church of considerable antiquity still standing the last of 12 mentioned in some records in 1740 the laying open of the churchyard of saint nicolas and saint francis in the sea cliffs is well described by gardener with the coffins and skeletons exposed to view some lying on the beach and rocked in cradle of the rude imperious surge of these cemeteries no remains can now be seen ray also says that ancient writings make mention of a wood a mile and a half to the east of dunwich the site of which must at present be so far within the sea this city once so flourishing and populace is now a small village with about 20 houses and 100 inhabitants there is an old tradition that the tailors sat in their shops at dunwich and saw the ships in yarmouth bay but when we consider how far the coast at low stoff nests projects between these places we cannot give credit to the tail which nevertheless proves how much the inroads of the sea in times of old had prompted men of lively imagination to indulge their taste for the marvelous gardener's description of the cemeteries laid open by the waves reminds us of the scene which has been so well depicted by bewick and of which numerous points on the same coast might have suggested the idea on the verge of a cliff which the sea has undermined are represented the unshaken tower and western end of an abbey the eastern isle is gone and the pillars of the cloister are soon to follow the waves have almost isolated the promontory and invaded the cemetery where they have made sport with the mortal relics and thrown up a skull upon the beach in the foreground is seen a broken tombstone erected as its legend tells to perpetuate the memory of one whose name is obliterated as is that of the county for which he was custos rotolorum a cormorant is perched on the monument defiling it as if to remind some moralizer like hamlet of the base uses to which things sacred may be turned had this excellent artist desired to satirize certain popular theories of geology he might have inscribed the stone to the memory of some philosopher who taught the permanency of existing continents the era of repose the impotence of modern causes the incursions of the sea at all borough were formerly very destructive and this borough is known to have been once situated a quarter of a mile east of the present shore the inhabitants continued to build farther inland till they arrived at the extremity of their property and then the town decayed greatly but two sand banks thrown up at a short distance now afford a temporary safeguard to the coast between these banks and the present shore where the current now flows the sea is 24 feet deep on the spot where the town formerly stood ethics harwich is said to have owed its rise to the destruction of orwell a town which stood on the spot now called the west rocks and was overwhelmed by an inroad of the sea since the conquest apprehensions have been entertained that the ithsmas on which harwich stands may at no remote period become an island for the sea may be expected to make a breach near lower dover court where beacon cliff is composed of horizontal beds of london clay containing septaria it had wasted away considerably between the years 1829 and 1838 at both which periods I examined this coast in that short interval several gardens and many houses had been swept into the sea and in april 1838 a whole street was threatened with destruction the advance of the sea is much accelerated by the traffic carried on in septaria which are shipped off for cement as fast as they fall down upon the beach these stones if allowed to remain in heaps on the shore would break the force of the waves and retard the conversion of the peninsula into an island an event which might be followed by the destruction of the town of harwich captain washington rn ascertained in 1847 that beacon cliff above mentioned which is about 50 feet high had given way at the rate of 40 feet in 47 years between 1709 and 1756 80 feet between 1756 and 1804 and 350 feet between the latter period and 1841 showing a rapidly accelerated rate of destruction among other losses it is recorded that since the year 1807 a field called the vickers field which belonged to the living of harwich has been overwhelmed and in the year 1820 there was a considerable space between the battery at harwich built in the beginning of the present century and the sea part of the fortification had been swept away in 1829 and the rest then overhung the water at walton nays in the same county the cliffs composed of london clay kept by the shelly sands of the crag reached the height of about 100 feet and are annually undermined by the waves the old churchyard of walton has been washed away and the cliffs to the south are constantly disappearing kent isle of shepi on the coast bounding the estuary of the tames there are numerous examples both of the gain and loss of land the isle of shepi which is now about six miles long by four in breadth is composed of london clay the cliffs on the north which are from 60 to 80 feet high decay rapidly 50 acres having been lost in 20 years between 1810 and 1830 the church at minster now near the coast is said to have been in the middle of the island in 1780 and if the present rate of destruction should continue we might calculate the period and that not a very remote one when the whole island will be annihilated on the coast of the mainland to the east of shepi is hern bay a place still retaining the name of a bay although it is no longer appropriate as the waves and currents have swept away the ancient headlands there was formerly a small promontory in the line of the shoals where the present pier is built by which the larger bay was divided into two called the upper and lower still further east stands the church of recalvir upon a cliff composed of clay and sand about 25 feet high recalvir regulvium was an important military station in the time of the romans and appears from lilan's account to have been so late as henry the eighth's reign nearly one mile distant from the sea in the gentleman's magazine there is a view of it taken in 1781 which still represents a considerable space as intervening between the north wall of the churchyard and the cliff sometime before the year 1780 the waves had reached the site of the ancient roman camp or fortification the walls of which had continued for several years after they were undermined to overhang the sea being firmly cemented into one mass they were 80 yards nearer the sea than the church and they are spoken of in the topographical britannica in the year 1780 as having recently fallen down in 1804 part of the churchyard with some adjoining houses was washed away and the ancient church with its two spires was dismantled and abandoned as a place of worship but kept in repair as a landmark well known to mariners i visited the spot in june 1851 and saw human bones and part of a wooden coffin projecting from the cliff near the top the whole building would probably have been swept away long ere this had not the force of the waves been checked by an artificial causeway of stones and large wooden piles driven into the sands on the beach to break the force of the waves end of chapter 19 part 3 section 46 of principles of geology this is a libervox recording a libervox recordings are in the public domain for more information or to volunteer please visit libervox.org recording by Dion John's Celtic city utah principles of geology by Charles Lyle chapter 19 part 4 isle of Thanet the isle of Thanet was in the time of the romans separated from the rest of Kent by a navigable channel through which the roman fleet sailed on their way to and from London BD describes this small estuary as being in the beginning of the eighth century three furlongs in breadth and it is supposed that it began to grow shallow about the period of the norman conquest it was so far silted up in the year 1485 that an act was then obtained to build a bridge across it and it has since become marshland with small streams running through it on the coast bedlam farm belonging to the hospital of that name lost eight acres in the twenty years preceding 1830 the land being composed of chalk from 40 to 50 feet above the level of the sea it has been computed that the average waste of the cliff between the north foreland and the recovers a distance of about 11 miles is not less than two feet per annum the chalk cliffs on the south of Thanet between ramsgate and pegwell bay have on an average lost three feet per annum for the last 10 years preceding 1830 goodwin sands the goodwin sands lie opposite this part of the kentish coast they are about 10 miles in length and are in some parts three and in others seven miles distant from the shore and for a certain space are laid bare at low water that they are a remnant of land and not a mere accumulation of sea sand as rental imagined may be presumed from the fact that when the erection of a lighthouse on this show was in contemplation by the trinity board in the year 1817 it was found by borings that the bank consisted of 15 feet of sand resting on blue clay and by subsequent borings the subjacent chalk has been reached an obscure tradition has come down to us that the estates of url goodwin the father of herald who died in the year 1053 were situated here and some have conjectured that they were overwhelmed by the flood mentioned in the sex and chronicle sub anno 1099 the last remains of an island consisting like sheppy of clay may perhaps have been carried away about that time there are other records of waste in the county of kent as at deal and at dover where shakespeare's cliff composed entirely of chalk has suffered greatly and continually diminishes in height the slope of the hill being towards the land there was an immense landslip from this cliff in 1810 by which dover was shaken as if by an earthquake and a still greater one in 1772 we may suppose therefore that the view from the top of the precipice in the year 1600 when the tragedy of king leer was written was more fearful and dizzy than it is now the best antiquarian authorities are agreed that dover harbour was formerly an estuary the sea flowing up a valley between the chalk hills the remains found in different excavations confirm the description of the spot given by caesar and antennas and there is clear historical evidence to prove that at an early period there was no shingle at all at dover straits of dover in proceeding from the northern parts of the german ocean towards the straits of dover the water becomes gradually more shallow so that in the distance of about 200 leagues we pass from a depth of 120 to that of 58 38 18 and even less than two fathoms the shallowest part follows a line drawn between romney marsh and balone from this point the english channel again deepens progressively as we proceed westward so that the straits of dover may be said to part two seas whether england was formerly united with france has often been a favorite subject of speculation so early as 1605 our countrymen versed again in his antiquities of the english nation observed that many preceding writers had maintained this opinion but without supporting it by any weighty reasons he accordingly endeavors himself to confirm it by various arguments the principle of which are first the proximity and identity of the composition of the opposite cliffs and shores of albion and gallia which whether flat and sandy or steep and chalky correspond exactly with each other secondly the occurrence of a submarine ridge called our ladies sand extending from shore to shore at no great depth and which from its composition appears to be the original basis of the itthmus thirdly the identity of the noxious animals in france and england which could neither have swum across nor have been introduced by man thus no one he says would have imported wolves therefore these wicked bees did of themselves pass over he supposes the ancient itthmus to have been about six english miles in breath composed entirely of chalk and flint and in some places of no great height above the sea level the operation of the waves and tides he says would have been more powerful when the straits were narrower and even now they are destroying cliffs composed of similar materials he suggests the possible cooperation of earthquakes and when we consider how many submarine forests skirt the southern and eastern shores of england and that there are raised beaches at many points above the sea level containing fossil shells of recent species it seems reasonable to suppose that such upward now in progress in sweden and greenland may have greatly assisted the denuding force of the ocean stream folkstone at folkstone the sea undermines the chalk and subjacent strata about the year 1716 there was a remarkable sinking of a tract of land near the sea so that houses became visible from certain points at sea and from particular spots on the sea cliffs from whence they could not be seen previously in the description of this subsidence in the phil trans 1716 it is said that the land consisted of a solid stony mass chalk resting on wet clay galt so that it slid forwards towards the sea just as a ship is launched on tallowed planks it is also stated that within the memory of persons then living the cliff there had been washed away to the extent of 10 rods encroachments of the sea at height are also on record but between this point and rye there has been a gain of land within the times of history the rich level tract called romney marsh or dungan s about 10 miles in width and five in breadth and formed of salt having received great accession it has been necessary however to protect it from the sea from the earliest periods by embankments the towns of lid and romney being the only parts of the marsh above the level of the highest tides mr redmond has cited numerous old charts and trustworthy authorities to prove that the average annual increase of the promontory of shingle called dungan s amounted for two centuries previous to 1844 to nearly six yards its progress however has fluctuated during that period for between 1689 and 1794 a term of 105 years the rate was as much as eight and one quarter yards per annum it is ascertained that the shingle is derived from the westward whether the pebbles are stopped by the meeting of the tide from the north flowing through the straits of dover with that which comes up the channel from the west as was formerly held or by the check given to the tidal current by the waters of the rother as some maintain is still a disputed question rye situated to the south of romney marsh was once destroyed by the sea but it is now two miles distant from it the neighboring town of winchelsea was destroyed in the reign of edward the first the mouth of the rother stopped up and the river diverted into another channel in its old bed an ancient vessel apparently a dutch merchantman was found about the year 1824 it was built entirely of oak and much blackened large quantities of hazelnuts peat and wood are found in digging in romney marsh south coast of england westward of hastings or of saint lenards the shoreline has been giving way as far as pavancy bay where formerly there existed a haven now entirely blocked up by shingle the degradation has equaled for a series of years seven feet per annum in some places and several martello towers had in consequence before 1851 been removed by the ordinance at the promontory of beachy head a massive chalk 300 feet in length and from 70 to 80 in breath fell in the year 1813 with a tremendous crash and similar slips have since been frequent about a mile to the west of the town of new haven the remains of an ancient entrenchment are seen on the brow of castle hill this earthwork supposed to be roman was evidently once of a considerable extent and of an oval form but the greater part has been cut away by the sea the cliffs which are undermined here are high more than 100 feet of chalk being covered by tertiary clay and sand from 60 to 70 feet in thickness in a few centuries the last vestiges of the plastic clay formation on the southern borders of the chalk of the south downs on this coast will probably be annihilated and future geologists will learn from historical documents the ancient geographical boundaries of this group of strata in that direction on the opposite side of the estuary of the ous on the east of new haven harbor a bed of shingle composed of chalk flints derived from the waste of the adjoining cliffs had accumulated at seaford for several centuries in the great storm of november 1824 this bank was entirely swept away and the town of seaford inundated another great beach of shingle is now forming from fresh materials the whole coast of sussex has been incessantly encroached upon by the sea from time immemorial and although sudden inundations only which overwhelmed fertile or inhabited tracks are noticed in history the records attest an extraordinary amount of loss during a period of no more than 80 years there are notices of about 20 inroads in which tracts of land of from 20 to 400 acres in extent were overwhelmed at once the value of the tithes being mentioned in the taxatio ecclesiastica in the reign of elizabeth the town of brighton was situated on that tract where the chain pier now extends into the sea in the year 1665 22 tournaments had been destroyed under the cliff at that period there still remained under the cliff 113 tournaments the whole of which were overwhelmed in 1703 and 1705 no traces of the ancient town are now perceptible yet there is evidence that the sea has merely resumed its ancient position at the base of the cliffs the site of the whole town having been merely a beach abandoned by the ocean for ages hamsher isle of white it would be endless to allude to all the localities on the sussex and hamsher coasts where the land has given way but i may point out the relation which the geological structure of the isle of white bears to its present shape as a testing that the coast owes its outline to the continued action of the sea through the middle of the island runs a high ridge of chalk strata in a vertical position and in a direction east and west this chalk forms the projecting promontory of culver cliff on the east and of the needles on the west while sand down bay on the one side and Compton Bay on the other have been hollowed out of the softer sands and our gelatious strata which are inferior in geological position to the chalk the same phenomena are repeated in the isle of perbec where the line of vertical chalk forms the projecting promontory of handfest point and swanage bay marks the deep excavation made by the waves in the softer strata corresponding to those of sand down bay hearst castle bank progressive motion of sea beaches although the loose papples and grains of sand composing any given line of sea beach are carried sometimes one way sometimes another they have nevertheless an ultimate motion in one particular direction their progress for example on the south coast of england is from west to east which is owing partly to the action of the waves driven eastwards by the prevailing wind and partly to the current or the motion of the general body of water caused by the tides and winds the force of the waves gives motion to pebbles which the velocity of the currents alone would be unable to carry forwards but as the pebbles are finally reduced to sand or mud by continual attrition they are brought within the influence of a current and this cause must determine the course which the main body of matter derived from wasting cliffs will eventually take it appears from the observations of mr palmer and others that if a pier or groin be erected anywhere on our southern or southeastern coast to stop the progress of the beach a heap of shingle soon collects on the western side of such artificial barriers the pebbles continue to accumulate till they rise as high as the pier or groin after which they pour over in great numbers during heavy gales the western entrance of the channel called the solent is crossed for more than two-thirds of its width by the shingle bank of hearst castle which is about two miles long seventy yards broad and twelve feet high presenting an inclined plane to the west this singular bar consists of a bed of rounded chalk flints resting on a submarine our gelatious space the flints and a few other pebbles intermixed are derived from the waist of horde well and other cliffs to the westward where tertiary strata capped with a covering of broken chalk flints from five to fifty feet thick are rapidly undermined in the great storm of november eighteen twenty four this bank of shingle was moved bodily forwards for forty yards towards the northeast and certain piles which served to mark the boundaries of two manors were found after the storm on the opposite side of the bar at the same time many acres of pasture land were covered by shingle on the farm of west over near limington but the bar was soon restored in its old position by pebbles drifted from the west and it appears from ancient maps that it has preserved the same general outline and position for centuries mr austin remarks that as a general rule it is only when high tides concur with a gale of wind that the sea reaches the base of cliffs so as to undermine them and throw down earth and stone but the waves are perpetually employed in abrading and fashioning the materials already strewed over the beach much of the gravel and shingle is always traveling up and down between high water mark and a slight depth below the level of the lowest tides and occasionally the materials are swept away and carried into deeper water owing to these movements every portion of our southern coast may be seen at one time or other in the condition of bear rock yet other beds of sand and shingle soon collect and although composed of new materials invariably exhibit on the same spots precisely similar characters the cliffs between hearst shingle bar and christ church are undermined continually the sea having often encroached for a series of years at the rate of a yard annually within the memory of persons now living it has been necessary thrice to remove the coast road farther inland the tradition therefore is probably true that the church of hordwell was once in the middle of that parish although now 1830 very near the sea the promontory of christ church had gives way slowly it is the only point between limington and pool harbour in dorset sure where any hard stony masses occur in the cliffs five layers of large ferriginous concretions somewhat like the septaria of the london clay have occasioned a resistance at this point to which we may ascribe this headland in the meantime the waves have cut deeply into the soft sands and loam of pool bay and after severe frosts great landslips take place which by degrees become enlarged into narrow ravines or chines as they are called with vertical sides one of these chines near boscombe has been deepened 20 feet within a few years at the head of each there is a spring the waters of which have been chiefly instrumental in producing these narrow excavations which are sometimes from 100 to 150 feet deep isle of portland the peninsulas of purbeck and portland are continually wasting away in the latter the soft argillaceous substratum kimmeridge clay hastens the dilapidation of the super incumbent mass of limestone in 1655 the cliffs adjoining the principal quarries in portland gave way to the extent of 100 yards and fell into the sea and in december 1734 a slide to the extent of 150 yards occurred on the east side of the isle by which several skeletons buried between slabs of stone were discovered but a much more memorable occurrence of this nature in 1792 occasioned probably by the undermining of the cliffs is thus described in hutchins history of dorset sure early in the morning the road was observed to crack this continued increasing and before two o'clock the ground had sunk several feet and was in one continued motion but attended with no other noise than what was occasioned by the separation of the roots and brambles and now and then of falling rock at night it seemed to stop a little but soon moved again and before morning the ground from the top of the cliff to the water side had sunk in some places 50 feet perpendicular the extent of ground that moved was about a mile and a quarter from north to south and 600 yards from east to west formation of the chesil bank portland is connected with the mainland by the chesil bank a ridge of shingle about 17 miles in length and in most places nearly a quarter of a mile in breadth the pebbles forming this immense barrier are chiefly salicius all loosely thrown together and rising to the height of from 20 to 30 feet above the ordinary high watermark and at the southeastern end which is nearest the isle of portland where the pebbles are largest 40 feet the fundamental rocks where on the shingle rests are found at the depth of a few yards only below the level of the sea the formation of that part of the bar which attaches portland to the mainland may have been due to an original show or reef or to the set of the tides in the narrow channel by which the course of the pebbles which are always coming from the west has been arrested it is a singular fact that throughout the chesil bank the pebbles increase gradually in size as we proceed southeastward or as we go farther from the quarter which supplied them had the case been reversed we should naturally have attributed the circumstance to the constant wearing down of the pebbles by friction as they are rolled along a beach 17 miles in length but the true explanation of the phenomenon is doubtless this the tidal current runs strongest from west to east and its power is greater in the more open channel or farther from the land in other words its force increases southwards and as the direction of the bank is from northwest to southeast the size of the masses coming from the westward and thrown ashore must always be largest where the motion of the water is most violent kernel reed states that all calcaria stones rolled along from the west are soon ground into sand and in this form they pass round portland island the storm of 1824 burst over the chesil bank with great fury and the village of chesilton built upon its southern extremity was overwhelmed with many of the inhabitants the same storm carried away part of the breakwater at plymouth and huge masses of rock from two to five tons in weight were lifted from the bottom of the weather side and rolled fairly to the top of the pile one block of limestone weighing seven tons was washed round the western extremity of the breakwater and carried 150 feet the propelling power is derived in these cases from the breaking of the waves which run fastest in shallow water and for a short space far exceed the most rapid currents in swiftness it was in the same month and also during a spring tide that a great flood is mentioned on the coasts of england in the year 1099 florins of wooster says on the third day of the nons of november 1099 the sea came out upon the shore and buried towns and men very many and oxen and sheep innumerable we also read in the saxon chronicle for the year 1099 this year eek on saint martin's mass day the 11th of november sprung up so much of the sea flood and so michael harm did as no man minded that it ever afforded and there was the ill day a new moon south of the bill or southern point of portland is a remarkable shoal in the channel at the depth of seven fathoms called the shambles consisting entirely of rolled and broken shells of perpura lapolis mitalus edulis and other species now living this mass of light materials is always in motion varying in height from day to day and yet the shoals remains constant end of chapter 19 section four