[meteorite-list] Chesapeake Impact Specifics?

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Wed, 29 Jul 2009 02:34:52 -0500
Message-ID: <C5C6DC04A3314A728F207B62B11A3168_at_ATARIENGINE2>

Hi,

    You missed the key sentence in the description:
"The impact structure is completely buried under
1000 to 1600 feet of sediment," meaning it's buried
under the sea floor of the Chesapeake Bay. The
features were located with drilling and mapped
with reflection studies. The Tom's River Canyon
crater is also under the sea.

    It's likely the sea was very shallow when it was
formed. It's very hard to determine when and how
much of the continental shelves are underwater at
any given time. Just 18,000 years ago, they were all
exposed, and the sea level was up to 400 feet lower
than now. The slope of the shelves is gentle, and
small rises and falls cover (and uncover) a lot of
territory.

    One lesson of this is how easy it is to hide a
humping big crater on an active planet like ours.


> don't want to pay the $32 to download it...

    For free:

    Here's a short summary from C. Wylie Poag:
http://www.lpi.usra.edu/meetings/lpsc97/pdf/1029.PDF

    And an abstract:
http://geology.geoscienceworld.org/cgi/content/abstract/30/11/995

    Here's a complete paper:
http://www3.imperial.ac.uk/pls/portallive/docs/1/3773904.PDF

    Big chunks of the ejecta landed 300 miles away,
in New Jersey. People are always dumping stuff in
New Jersey...
http://www.oceanleadership.org/files/USSSP/PDFs/Greatest_Hits/Events/McHugh.pdf

    The secondary craters are detailed here:
http://www.lpi.usra.edu/meetings/LPSC99/pdf/1047.pdf

    Here's the stratigraphy, blah, blah...
http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1019.pdf

    Here's a 61-page book on the effects of the crater.
Might as well download it for free -- your tax money
paid for it!
http://pubs.usgs.gov/pp/p1622/p1622.pdf

    Here's another book, an 85-pager, that you paid for...
http://pubs.usgs.gov/of/2004/1016/2004-1016.pdf
with lots and lots and lots of articles!

    Go crazy, EMan.



Sterling K. Webb
-----------------------------------------------------------------------------
----- Original Message -----
From: "Mr EMan" <mstreman53 at yahoo.com>
To: "metlist" <meteorite-list at meteoritecentral.com>
Sent: Wednesday, July 29, 2009 1:36 AM
Subject: Re: [meteorite-list] Chesapeake Impact Specifics?


> Ok Ok ok... I found this article cited (but don't want to pay the $32
> to download it):
> "Ancient impact structures on modern continental shelves: The
> Chesapeake Bay, Montagnais, and Toms Canyon craters, Atlantic margin
> of North America by C. Wylie Poag, Jeffrey B. Plesciab and Phillip C.
> Molzera" in "Deep Sea Research Part II: Topical Studies in
> Oceanography
> Volume 49, Issue 6, 2002, Pages 1081-1102
> Ocean Impacts: Mechanisms and Environmental Perturbations " and it
> cites 23 additional craters associated with Chesapeake Not including
> Tom's( River) Canyon. I assume these are all subsurface. Anyone with
> access to the article, does it have a graphic/map for this crater
> field or explain how they were located?
>
> Looking at the cross section at Wikipedia; the breccia "pile" is 99%
> contained in the buried crater so it may be 4200ft thick and the
> central peak is far below the rim of the crater so it may be 3000ft
> high. What the author failed to mention is that the whole structure
> is more than a half mile below ground level!
>
> I guess all things are relative but we fail to grasp the relationships
> at times--in this case to "sea level". Speaking of sea level which we
> know varies over time-- the new testament speaks of the "Sermon on the
> Mount". Well been there and done that and the "Mount" is about the
> size of a buried school bus--AND it is about 400 ft below sea
> level--another thing not depicted correctly in 2000 years of bible
> inspired art.
>
> Elton
>
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Received on Wed 29 Jul 2009 03:34:52 AM PDT