Bauman Impact Crater

of Central Montana

Hypothesis and presentation of supporting evidence that the hexagonal shaped geology observed in central Montana is the result of an impact from a large asteroid type object.


Central Montana is my home ground.  I have always been curious about my surroundings and as a young boy I became interested in science and how things worked, especially space, geology, and physics.  And now, fifty years later, I believe that I have discovered a major surface feature that would help explain a number of geologic anomalies associated with central Montana.  Specifically I have discovered a large impact crater or impact basin that covers between one ninth and one sixth of the entire state.  I have identified at least two fracture zones that define this structure; an inner hexagonal shaped ring that outlines the primary fracture zone and an outer vee shaped area that follows the same angular pattern and is part of a secondary ring that expands the fracture zone to the south.  Both are clearly visible on a Montana 3-D map printed in 1977 by Kistler Graphics - first observed in June of 2001.  I have looked at a number of maps and other images such as satellite and digital images over the past few years and none of them show the impact zone in such clear detail and in such high relief as this particular map.  Since no one else has brought this geologic feature to the attention of the world, I thought I would, I therefore declare that this geologic structure be known as the Bauman Impact Crater.


My name is David D. Bauman; I was born in Lewistown Montana in 1951 and lived in central Montana until 1975.  I grew up at Eddies Corner during this time because my dad was part owner and our family lived close by.  Eddies Corner has been a family business since 1949 when my grandfather bought it from two guys named Ed.  My uncles still own and operate it today.  I worked at the service station until I graduated from Moore High School in 1970.  I then attended Montana State University in Bozeman where I studied geology.  My classmates and I would discuss various odd formations that are unique to central Montana.  Admittedly, this was just an introduction to the complex science of natural geology and I do not claim to possess the knowledge of a true professional.  However, I still intend to make my case and to present a convincing argument to support my hypothesis.   I would ask that if anyone has information to support my claim - that this geologic feature was created by a collision with a large object from space - that they would come forward and say so.  And dare I ask?  If anyone has evidence that would disprove my claim, that they would also come forward and say so.  I would much prefer supporting evidence or at least some constructive critique and not just contrary criticism.  Can you please help me out?  My observation is presented here as a hypothetical concept that is intended to further the quest for knowledge.   


Let’s start with the visible evidence.  There is a definite geometric shape centered on my map of Montana.  The outlines of this shape circumscribe an almost perfect hexagon.  I count six sides and six corners.  My research suggests that the hexagon shape is the result of an oblique angle of impact.  I also study astrophysics and have found images of craters on other bodies in the solar system that show the same angular pattern.  Current understanding says that the results of an object of sufficient size and velocity striking at a low angle of incidence are not circular but angular.  I believe that this pattern reflects the way a shock wave is propagated by a glancing blow from a very large object.  If I was to guess I would say that this object was an extremely large asteroid or a small planetoid.   Some impact craters that we can see on other bodies throughout the solar system have a central cone or rebound peak - this crater does also.  It is in the form of a structure called the Judith Mountain Group.  They form a central cone clearly in the middle of the central ring.  Let me quote Roadside Geology of Montana (RGM), “large masses of magma rose, one after the other, into this area about 50 million years ago, pushing through the rock formations beneath the plains like great pistons” (Alt & Hyndman, 1997 p.332) (`a).  This comment is in reference to a group of igneous intrusions that are geologically similar; the North and South Moccasin Mountains, the Judith Mountains, and Black Butte.  RGM goes on to say that, “The rising masses of magma popped up the sedimentary formations above them as though they were trapdoors hinged at one edge and now we find these older formations tightly wrapped around the younger intrusive masses”(`a).

Can you begin to get a vision for what we are really looking at here? 

I believe that what I see here is a rebound cone that popped back after the initial shock wave fractured the crust of the earth in this very spot.  The enormous amount of energy released downward was then reflected and released upward to form the ‘Great Pistons’ and ‘Hinged Doors’ that RGM writes about.  They also go on to say that, "large exposures of pale gray Madison limestone, rock normally several thousand feet down in this part of Montana, are especially conspicuous”(`a).  This seems to indicate a highly localized force of great power. 

        Also worth mentioning are the quartz phenocrysts found at the top of Judith Peak.  Unusual crystals of smoky or black quartz are in the dikes southeast of the old radar site.  And found close by is a particular variety of quartz known as the Dobe Diamond; it has the unique hexagonal shape of a six sided double ended prism.  A coincidence that I will take as a sign I am on the right path and proceed undaunted with my concept that an impactor of enormous size is responsible for the unique geology of central Montana.  As many would know, the Judith Mountains were named by Captain Meriwether Lewis, of Lewis and Clark fame, to impress his girlfriend back east.  These men were explorers for the Corps of Discovery that passed through this area in 1805, so in that same spirit of discovery I shall continue to explore and to examine new concepts.  


 Next in line is the Ring of Fire.  If we look at the different mountain ranges that lie along the outline of the inner hexagon, we find a series of igneous intrusions and volcanic activity.  To the west we have the great granite stocks of the Little Belts that intruded the older strata with a swarm of laccoliths; a laccolith is a plutonic structure that invaded the sedimentary layers from below with molten magma, creating an underground blister.  Continuing clockwise we have the volcanic Highwood Mountains along with all their associated dikes and laccoliths, including Square Butte and Round Butte. To help explain further: the molten rock that solidified under the surface is an intrusion and molten rock that solidified above the surface is an extrusion. So, the lava of volcanoes is extruded magma that came from below and flowed out on top of the existing surface before it cooled down and solidified.  Intrusions: like dikes, diatremes, laccoliths, batholiths, and stocks are also made of magma, which is the same or similar material except that it cooled down much slower under the surface.  Later, as the forces of erosion do their work we are left with a view of an old laccolith like Square Butte.  On to the north we have the Bearpaw Mountains, an isolated cluster of volcanoes that include a number of spectacular igneous intrusions along with equally impressive igneous extrusions.  Continuing on to the east we have the Little Rocky Mountains, a sharp dome punched in the plains by a huge igneous intrusion surrounded by steeply tilted sedimentary rock.  Igneous intrusions seem to be a recurring theme through out the impact basin.  But please notice that all of this igneous activity surrounds one great exception to the rule and that is the Snowy Mountains.  It begs the question; how did a block of sedimentary rock get pushed up right in the middle of all this plutonic activity?  It is incongruent, it doesn’t make any sense, and under normal circumstances it doesn’t fit together.  So I propose that in order to make sense of it all, that we think of the area inside of the hexagonal ring as fractured plates.  Fairly large fractured plates mind you, not unlike the hinged trapdoors that were mentioned earlier.  One of the largest of these unhinged plates received a shove in the proper direction and became what we now call the Snowy Mountains.  The Snowies are what is known as a block uplift mountain; a section of the earth’s crust that was lifted up and tilted on edge.  It is a crustal arch that exposes layers of rock that would otherwise be thousands of feet below the surface.  Let’s be clear;  I don’t think that the Snowy Mountain plate immediately popped out of the ground when the impact occurred.  However, I do think that the crust was immediately fractured into plates by an impact from a large space rock about 50 million years ago. And then shortly after that impact the mountains of the inner ring were formed as enormous pressures from below were released.  Magma pockets were opened up and the concentrated pressure of the compressed lower strata pushed up from below. 

       Due to the geology of plate tectonics compressional forces develop as the continent moves to the west.  These forces were stored up over time.  And then because of the shock effect of an asteroid impact the pent-up compressional energy of 100 million years was released and the fractured plates moved up and moved apart.  The unhinged plates floated higher on the denser mantle material below and magma filled the cracks as they developed in the crust above.  It looks to me like the Snowy Mountain plate got a particularly powerful shove that pushed the northern part down and lifted the southern part up.


Over eight thousand feet of vertical lift has revealed the stratified layers of over 500 million years of sedimentary deposits, deposits that were laid down in a shallow sea teaming with life.  Indeed, we can find fossilized sea creatures on top of and buried within the sedimentary strata of the Snowy Mountains.  Trilobites and brachiopods from the Cambrian period, crinoids and corals from the Carboniferous period, old oysters, ammonites, and squid like belemnites from the Jurassic period and even some sharks in the Bear Gulch formation that have been perfectly preserved for over 230 million years.  All this came from the bottom of an ancient sea that is now part of a high mountain. 


I would like to quote from Physical Geology by Leet and Judson, one of my text books:

The Rockies are Fold Mountains; fold mountains provide us with spectacular examples of deformed rocks. The numerous folds of anticlines and synclines have been sliced open to view by streams cutting into them as the land moved upward from forces causing a rise in elevation. The lands against which these rocks were pushing now stand as plateaus; broad, high-standing regions underlain by sedimentary rocks relatively little deformed” (Leet & Judson, 1965, p.264).  Picture a horizontal zigzag like a piece of paper that is pleated on one half and flat on the other and then the whole thing is pushed together and bent upward – so that half is crumpled and half is relatively flat, but the whole thing is under elastic compression and bowed upward.  Think of a box compactor full of rubber balls and floating on top is a piece of sheet rock precisely cut to completely cover the area from side to side and from end to end.  Now have someone turn it on while you stand in the middle.  Wait until the ends start to come together and the balls are compressed and the sheet rock starts to bend upward.  This is a mental model of the conditions in central Montana about 50 million years ago.  So now I would like to point out that the Bauman Impact Structure sits squarely on the border between the Rocky Mountain Chain and the Great Plains of North America.  The hexagonal ring is right on the edge between the folded mountains to the west and the raised plateau to the east.  The crust in this area of central Montana would have been relatively weak and probably pocketed with hot spots of magma, even though it was relatively little deformed at the time.  Still, the rocks under it were under tremendous compression and starting to bow upward, however they had not reached their elastic limit yet. To the east was a relatively flat plateau that continued on for hundreds of miles. To the west was, and still are, the numerous folds of the Rocky Mountains that had developed into a series of basically parallel ridge lines that lie about 30 degrees from geographic north.  My point is that the ridge line of the Snowy Mountains is about 80 degrees from geographic north, a huge departure from the general trend of the mountain ridges that begin less than 100 miles away. This departure from the general trend should be an indication that the forces that created the Snowy Mountains are separate from the forces that created the Rocky Mountains immediately to the west.  Back to our mental picture of you standing in the middle of the compactor; now jump on the sheetrock.  What do you think will happen?  The surface will break into pieces and the whole mass will rebound and increase in elevation.  I believe the shock wave from a large meteor impact triggered a combination of elastic, plastic and brittle deformation reactions.  The crust of the earth was under stress from below and did not have the strength to withstand the strain of impact.  Hence we have fractures, breaks, and uplifted plates.  One of these plates, the Snowy Mountain plate, looks like an asymmetrical fold where the strata was pushed up and severely stretched on the steep side of the fold. The breaking point of the upper strata was exceeded and the upper layers of rock broke away, but the middle and lower strata were pliable enough to bend. They were bent up and bent over, forming the folded block we see today; comprising the south face (south limb), top ridge (east/west strike), and north slope (north limb) of the mountain block.   It looks like the kind of fold that would be developed if you took your boot and kicked the surface of a rug in such a way that it created a single fold.  Better yet, cover the rug with mud and let it dry a little bit for more realism.  The upper crust would crack and fall away but the bottom layer would bend and remain part of the fold.  According to current understanding; Fold Mountains created by compression always result in a series of parallel folds that form together, so that there is more than one ridge line, meaning more than one fold.  The Snowy Mountains are a single fold that stands alone and is therefore out of the ordinary and probably not caused by common compressional forces.  It looks like a gigantic scuff mark caused by something that ripped into, then dragged and deformed the outer skin to leave a giant scab on the surface of the plains.  Consider the results of an extremely shallow angle of impact from an extremely large object.


The Little Belts take a beating:  Because they are located at a focal point of the hexagonal ring, they were most likely influenced by the impact.  Since the Little Belt Mountains were already in existence they should show some sign that there were shock effects at work.  Therefore we should see a combination of folds, faults, and unique geologic anomalies.  And this is exactly what we observe.  In fact the Little Belts are home to one of the most unusual gem stones in the world – the Yogo Sapphire.  I am told that a sapphire can only develop at pressures and temperatures that are found at the mantle level.  The question is, how can a sapphire that developed deep below the crust be brought to the surface and exposed?  I believe that the Yogo Sapphire is a direct result of the shock effect.  Whether the sapphires were blasted up through a fissure that opened up, or whether they were already close to the surface and were subsequently morphed into their present form by a shock wave is yet to be determined.  But no matter which way the sapphires were formed, their existence can still be directly attributed to the impact of an asteroid about 50 million years ago. 


And just because my so called Ring of Fire is relatively flat and bare looking to the east doesn’t mean that there are not significant surprises to be uncovered there.


The Last Diatreme: from the macroscopic to the microscopic.  Think shock-metamorphosis of quartz and planar deformation features or PDF for short.  A diatreme is a small igneous intrusion generally shaped like a dike or vertical cylinder composed of peridotite (an igneous rock composed essentially of augite and olivine) derived directly from the earth’s mantle.  A diatreme carries material from the mantle level to the surface of the earth’s crust.  I am continuing my research while I am writing this paper and to be honest I had forgotten this fact until I read about the Smokey Butte diatreme just west of Jordan.  By a strange coincidence I had picked up my copy of Roadside Geology of Montana once again and was attracted to a section about Jordan, MT.  My father’s family and mother’s family both lived in Jordan, so I have roots there.  I was intrigued by what RGM had to say, “Smokey Butte is a butte because it contains a diatreme, one of those small igneous intrusions that punched up from the earth’s mantle about 50 million years ago.  Most of Montana’s diatremes are in the central part of the state; this is the easternmost known outpost of that activity, and it contains two of Montana’s most interesting discoveries.”  (1) “A French mineralogist found in it a mineral called armalcolite that is otherwise known only in rocks collected on the Moon.” (as in full of impact craters)  And “the rocks exposed in Smokey Butte contain a thin layer of the dark sediment that marks the boundary between Cretaceous and Tertiary (Paleogene) time everywhere in the world that rocks of that age exist.” (Alt & Hyndman, 1997, p.411)(`b).  This is the thin layer of dust that marks the end of the dinosaurs reign, the K-T or K-Pg boundary, recognized because of its high content of iridium.  And (2) “More than this, the fatal layer also contains a material far more incriminating than iridium, an extremely rare mineral called stishovite, a distinct variety of quartz that forms only in explosion-shocked rocks.”… “The dust layer at Smokey Butte also contains mineral grains full of microscopic fractures in a pattern known to occur only in rocks shattered in extremely violent explosions.”  To further quote RGM, “The shocked mineral grains and stishovite at Smoky Butte provide the most conclusive evidence so far found to support the theory that the dinosaurs did indeed die under a dark cloud of dust ejected from a big meteorite explosion crater.”(`b)

Maybe, just maybe, there was more than one crater event.  What if the crater event in Central Montana played a part?  Even if it was 15 million years after the Chicxulub Impact, the Bauman Impact Event may have brought evidence to the surface.  Or maybe this impact resulted in some world class events of its own.   


Massive Dynamics; let me restate the obvious: It is not by coincidence that the hexagon shape in central Montana and the hexagon shape on other bodies in the Solar System look the same.  There is a definite correlation between cause and effect at work here. Since physics is the same throughout the universe; it follows that if the hexagon shape on other bodies in the universe was caused from an impact then the hexagon shape we see here on earth was also caused from an impact. So now look closely at the images of Ptolemaeus, Alphonsus, and Albategnius, the impact craters in the central region of our own Moon.  They are definitely angular and hexagon in shape.  There is no doubt that these are impact craters.  Therefore there is little doubt that the hexagon shaped geology in central Montana was also caused from an impact, and is in fact an impact crater.  As a matter of further proof, consider Gula and Achelous, impact craters on Ganymede, a moon of Jupiter.  They also show a decidedly angular shape, plus there is a noticeable secondary ring around both of these craters that shows an angular pattern.  I believe that this feature is an outer ring caused from shock wave fracture and it is not just ejecta splatter that we observe.  And there are many other examples out there; consider Tindr crater on Callisto, also a moon of Jupiter, this impact shows similar angular features, and Mimas a moon of Saturn which has a huge hexagonal crater, and Iapetus another moon of Saturn that has multiple hexagonal craters, and the planet Mercury also has hexagonal craters, and dwarf planet Ceres has hexagonal craters, and the list goes on.  So now back to earth.  I believe that because the object that struck central Montana was extremely large it was not totally vaporized in an explosive reaction, but rather imparted most of its kinetic energy into a deep and penetrating shock wave.  Think of the difference in energy between a small hammer and a large hammer, or the explosive energy of a small caliber bullet compared to a large caliber bullet.  In a similar fashion a small object moving at high velocity tends to explode on impact and thus create a circular crater.  The explosive energy release is circular even when impacting at a shallow angle of contact.  But with objects of sufficient size and shape, and if the angle of approach is shallow enough, the explosive component will not be enough to cause the object to totally vaporize.  To be sure, part of the objects mass will be converted into explosive energy and vaporize, but part of the objects mass will continue on and its momentum of contact will be converted into a shock wave.  So we have both explosive cratering and shock wave fracturing all from the same impactor.  I believe that when the size, speed, and angle of impact are combined in just the right proportions the result is a hexagonal impact crater.  Still, the truth is not based on what I believe.  The truth is based on what the facts are.  And the fact is I see a pattern.  As a matter of fact I see the hexagon shape of a shock wave crater.  What about you?


How big is the crater?

According to my measurements, the distance from the west side, where Belt creek passes by Belt, to the east side, where the Musselshell River passes by Mosby is about 140 miles across.  Likewise measuring from where the Missouri River passes by Fort Benton to where the Musselshell River passes by Roundup is also 140 miles.  And if I start from where the fracture line would be if the Little Rocky Mountains had not covered it up with a mountain at Zortman and measure across to where the Musselshell passes close to Martinsdale, I get about 135 miles.  Obviously the Musselshell River follows part of the fracture line and the Missouri River follows another part of the fracture line.  Because the Bearpaw Mountains developed at the northern point of the fracture zone the Missouri River was forced to go around.  And the Missouri followed a similar detour because of where the Little Rocky Mountains developed.  Still for the most part the rivers follow the old fracture line, which would make sense from a geologic point of view. 

The bottom line question is; is it possible?  The answer is - yes it is possible.  And if there is enough supporting evidence, not only possible but probable.  But before you decide that I don’t know what I am talking about, please read my entire presentation before you comment.  What I really want to know is: Do the real world facts fit the hypothesis?  There is no doubt that more research is necessary.  I am fully aware that there are smarter people than me out there that have the answers.

Please consider this impact event a real possibility and please be considerate in your critique. 

To quote Sir Isaac Newton, "No great discovery was ever made without a bold guess."

Thank you. Dave Bauman.  email: [email protected]

Selected References

Alt, David and Hyndman, Donald W. (1997) chap. The Judith and Moccasin Mountains, title Roadside Geology of Montana.  Mountain Press Publishing Co., Missoula, MT.


Leet, L. Don and Judson, Sheldon (1965) chap. Mountains and Mountain Building, title Physical Geology, third edition.  Prentice-Hall Inc., Englewood Cliffs, NJ.