Friday, September 27, 2013

Chesapeake Bay Crater; the Moon's Early Years

We're learning more about a crater under Chesapeake Bay's mouth, and may have a better explanation for how our moon formed.
  1. Virginia's Changing Shore and an Eocene Impact
  2. Fine-Tuning Lunar Origins

(Joe Tucciarone, via NASA, used w/o permission.)

Living With Vastness

"Nothing endures but change."
(Heraclitus, 540 BC - 480 BC)
Quite a bit changed in the two dozen centuries since Heraclitus said that, and change still happens. It's a constant in this universe.

Some change is a familiar part of everyday life:

"5 It sprouts green in the morning; by evening it is dry and withered."
(Psalms 90:5-6)
Other changes didn't become apparent until we began learning how to study evidence left in Earth's rocks and soil.

I don't mind living in a universe that's almost unimaginably ancient and constantly changing. Even if I did, there isn't much I could do about the situation. God's God, I'm not, and I'm okay with that.

I think accepting that God's preferences outvote mine comes pretty close on the heels of realizing that God is large and in charge. Putting it more conventionally, fear of the Lord is the beginning of wisdom. (Proverbs 9:10)

It's increasingly obvious that the Almighty decided to create a universe that's constantly changing: and very, very old by human standards. Again, I'm okay with that. If anything, today's knowledge about this universe increases my awe of its Creator.

Ussher, Galileo, and Keeping Up

Up to about four centuries back, an educated person could reasonably assume that the universe was about 6,000 years old and no more than several thousand miles across.

James Ussher, an English king's Primate of All Ireland and no friend of "papists," published his opinions about when creation happened in 1650 and 1654.

From his literary and historical research, Ussher decided that creation happened at nightfall before October 23, 4004. In 1650, his work was impressive scholarship: at least in the British Isles.

Meanwhile, folks like Copernicus and Galileo were following up on speculation that had prompted Proposition 27/219: in 1277, four centuries earlier.

Galileo and Copernicus were scientists and Catholic, and that's another topic. Topics:

Using Our Brains

I still run into some folks who say Christianity is stupid, because Christians don't 'believe in' science. Surprisingly, I also run into a few Christians who insist that science is a lie because "it's not in the Bible."

I don't see a problem with believing that a rational creation and a rational Creator exist.

Using our brains is okay: but we're expected to use them wisely. Science and technology, studying this astounding creation and developing new ways of using it, are part of being human. (Catechism of the Catholic Church, 35, 159, 2104, 2293)

Mesopotamian Cosmology

I suspect that part of the trouble some folks have with accepting what we've learned about this universe is its scale. It's enormous, in terms of both space and time.

Western civilization's current iteration inherited a great deal of knowledge from the ancient world: including a variation of Mesopotamian cosmology. Today it's mostly important as poetic imagery. (Genesis 1:2; Daniel 7:2; Psalms 150:1)

Back in the 'good old days,' ancient cosmological models were reasonable, even if taken literally. They're still good settings for fantasy role playing games, and that's yet another topic.

(From "The Three-Story Universe," © N. F. Gier, God, Reason, and the Evangelicals (1987), via Nick Gier, University of Idaho, used w/o permission.)

The Mesopotamian model works quite well, for folks living away from large bodies of water. Earth's curvature is hard to miss on anything wider than Minnesota's Lake Winnibigoshish. (Yes, the name sounds funny: but it's real.)

Tilting Lakes: or, North America's Massive Hangover

"Effects still felt from last ice age"
Rob Swystun, Central Plains Herald Leader, (September 4, 2009)

"Like a massive hangover after the bachelor party of the millennium, Lake Manitoba, Lake Winnipeg and the rest of the province are all still feeling the effects of the last ice age from over 10,000 years ago.

" 'People somehow assume that these lakes have been the same for thousands of years and will be the same for thousands of years, but they're not,' Delta Marsh Field Station manager Gordon Goldsborough said recently on a short break during a typically busy day at the station.

"In fact, the lakes are tilting....

"...Around 10,000-20,000 years ago, during the last ice age, Canada was underneath massive sheets of ice anywhere from three to five kilometres thick, he [University of Minnesota Department of Geology and Geophysics's Harvey Thorleifson] said.

"These massive sheets of ice pressed down on the land with great force, and once they receded, leaving an enormous lake that has since been named Glacial Lake Agassiz in their wake, they let the downward force off the land, causing it to rebound. When Glacial Lake Agassiz drained, it left behind Lakes Winnipeg and Manitoba....

"...Hudson Bay was the centre point for the glacial ice sheets.

" 'Placing the ice sheet on Hudson Bay was like placing a bowling ball on a trampoline,' he offered...."
I live near the center of Minnesota, roughly 300 miles south of Canada. The local landscape is what happens when several kilometers of glacier melts. Parts of it are changing, fast. What was a lake in my youth is now two large ponds and a marshy meadow.

Glacial Lake Agassiz is now the Red River Valley of the North: some of the best, and flattest, farmland on the planet. Where I live, the landscape is mostly sand and gravel with a little soil on top.

Unused sand pit in central Minnesota. (2009)

Sauk Lake Park, Sauk Centre, Minnesota. (2009)

My town is near the south edge of Minnesota's lake country: another leftover from those glaciers. Our lakes are filling in, too: but until they do, we've got some very picturesque scenery.

1. Virginia's Changing Shore and an Eocene Impact

(USGS, via, used w/o permission)
"Effects of Ancient Meteor Impacts Still Visible on Earth Today"
Nola Taylor Redd, (September 23, 2013)



Numbers in the first and third paragraphs don't seem to match: "...a 15-story wall of water..." and "...a massive wave 1,500 feet (457 meters) high...."

Looks like someone dropped a zero, since otherwise those floors would have to be an average of 100 feet apart. The 1,500 feet to 457 meters conversion is fairly accurate, by the way, and matches another article's number:
Although we call it the Chesapeake Bay Crater, Chesapeake Bay wasn't there until recently: geologically speaking. For that matter, the Atlantic Ocean wasn't around until Earth's continents started breaking up more than 100,000,000 years back:

(From, used w/o permission.)

(From USGS, used w/o permission/)

Actually, it looks like the Atlantic began when Earth's continents started breaking up again.

(From, used w/o permission.)

Extinctions and Coincidence

The Chesapeake Bay and Popigai impacts happened very roughly at the same time as another of Earth's extinction events. Unlike what happened 65,000,000 years ago, it doesn't look like impacts set off the Eocene–Oligocene extinction event:
Even so, the east coast of North America wasn't a good place to be when something blew a 90-kilometer-wide hole in the ocean floor where the mouth of Chesapeake Bay is now.

Earth: a Falling Rocks Zone

"Near-Earth Objects Impact Our Lives"
Langley Research Center, NASA (August 29, 2013)

"...An enormous tsunami modeled at 1,500 feet (457 meters) rushed westward, Johnson says, and engulfed the land to the foot of the Blue Ridge Mountains.

"At the time of the impact, sea level along the East Coast was much higher and most of eastern Virginia was submerged. According to Johnson, the ancient shoreline was somewhere in the vicinity of Richmond before the impact.

"Johnson stated that the Chesapeake Bay itself did not form until after the Wisconsin glaciation ice sheet melted 18,000 years ago.

"Discovery of the giant crater revised our understanding of Atlantic Coastal Plain evolution. Studies revealed several consequences of the impact that still affect citizens around the bay today: land subsidence, river diversion, disruption of coastal aquifers, ground instability, and location of Chesapeake Bay.

"Though we have learned much from the geology of the Chesapeake Bay crater, Dan Mazanek, a near-Earth object (NEO) expert at NASA Langley, explained that there is still much left to learn...."
Among other things, we don't know exactly what made that crater. It could have been an asteroid, a comet, or part of a larger bit of debris that made the Toms Canyon structure in New Jersey and maybe the Popigai crater in Siberia.

As I've said before, between exploding mountains and debris falling out of the sky, Earth is a dangerous place

More about the Chesapeake Bay crater:
My hat's off to professor emeritus Gerald Johnson, for pointing out yet another well-known landmark that's younger than humanity. We'd been using fire for well over 982,000 years, and sewing for more than seven millennia, by the time a river valley flooded, forming today's Chesapeake Bay.

2. Fine-Tuning Lunar Origins

(NASA/JPL-Caltech, via, used w/o permission)
"The Moon Is 100 Million Years Younger Than Thought"
Mike Wall, (September 23, 2013)


"The leading theory of how the moon formed holds that it was created when a mysterious planet - one the size of Mars or larger - slammed into Earth about 4.56 billion years ago, just after the solar system came together. But new analyses of lunar rocks suggest that the moon, which likely coalesced from the debris blasted into space by this monster impact, is actually between 4.4 billion and 4.45 billion years old.

"The finding, which would make the moon 100 million years younger than previously thought, could reshape scientists' understanding of the early Earth as well as its natural satellite, researchers said...."
The difference between 4,560,000,000 and 4,400,000,000 isn't much, but it makes a big difference for folks trying to sort out how Earth and our moon formed.

The Solar system's age is pretty well defined: right around 4,568,000,000 years back. Part of the problem is that planets like Earth kept changing after those early eras. Asteroids like Vesta haven't changed much in the last 4,400,000,000 years. Meanwhile, Earth's crust has been rearranged: a lot.

If the latest analysis is right, and our moon formed when something nearly as large as the pre-lunar Earth ran into our planet, it would explain why the Earth and moon have an almost identical selection of elements.

Then there's the question of what happened to Earth's atmosphere. It could have been blown off entirely, replaced with the start of our current mix later: or not. Either way, conditions near Earth's surface made a difference in how life emerged and developed.

More about Lunar origins:
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