[meteorite-list] TV program on ASTEROIDS/ Cont. Drift/ OT

From: EL Jones <jonee_at_meteoritecentral.com>
Date: Thu Apr 22 10:00:10 2004
Message-ID: <3D3F8885.509DC0F5_at_epix.net>

A bit off topic but, did anyone notice that the animation of the Chuxilub
impactor in tonight's program shows the Earth as it is today..... and not as it
looked 65 million years ago?

When Chuxilub struck.... North America and South America were not connected.
What we today call Central America was a series of Islands. In what we know
today as North America: Florida was ocean floor, The coast of North America in
the east was the"Fall Line". The fall line-- named so because water falls
stopped riverboat traffic where the resistant walls of rock created rapids. It
is a curve stretching from Auburn, Alabama through Columbus And Macon Georgia
up to and beyond Anderson SC. This is the edge of an ancient and huge
granitic/gniess batholith which gives rise to Stone Mountian near Atlanta. Being
more resistant to erosion, it was the ancient rocky coast of Eastern North
America. It was was the coast from 85 mybp to around 40 mybp.

The Mississippi River delta didn't exist because most of the central United
States was an inland sea. (That and the fact that at that time, the Ancient
Mississippi River emptied towards the ancient St. Lawrence River-- before the
ice sheet that formed the Great Lakes diverted the drainage southward.
Somewhere in the vicinity of Utah, Idaho, and South Dakota over to West
Virginia was the "southern" coast of North America.

While on the subject of ancient land forms, there is a book (Dodds? Le Claire?)
on meteorites which is overall good but has a section on "a line of craters" in
Canada and how by "some unkown design", asteroids seemed to always fall in the
"same place" on the globe. A fallacy in his analysis was the orientation and
location of the Canadian Shield throughout time. Seems asteroids weren't
falling always on the same coordinates on the globe so much as as Canada was
roaming and rotating to be at the right place and time over the eons to catch
them. Not withstanding the collection of astroblemes, the shield is one of the
rare places on Earth where crustal rocks have been largely undisturbed since
early geological history. Craters haven't eroded away as they have elsewhere on
earth.

At the Vienna Museum of Natural History is an exhibit which lets the visitor
spin a large pilot wheel, while viewing a monitor, it smoothly moves the land
masses of the earth continuously from about 2-1.5 billion years ago through the
present and, on forward for 20-30 million years. One can stop off in any year
they wish to see what the surface of the world looked like then. Incidentally,
some 5-10 million years from now the Mediterranean Sea will be the Mediterranean
Mountains! I'd love to have that program so I could follow astroblemes through
time.

Just some perspective....

Regards,
Elton
Received on Thu 25 Jul 2002 01:12:06 AM PDT