[meteorite-list] Charity Shoal (Crater???), Lake Ontario

From: Keith <littlejo_at_meteoritecentral.com>
Date: Thu Apr 22 10:08:27 2004
Message-ID: <Pine.SOL.4.33.0209162016240.16956-100000_at_katie.vnet.net>

In the thread " was "Thank You for Crater Information"
On Mon, 16 Sep 2002 11:22:28 -0400
Charles O'Dale codale0806_at_rogers.com wrote:

>Thank you for the responses to my Can-Am crater
>question. The research so far points to an impact
>in southern Lake Huron post-Grenville but not =
younger than early Paleozoic. The investigation
>continues....
>
>Does anyone have any information on Charity Shoal in
>eastern Lake Ontario? The inference is that it is
>another impact event that is not been completely
>documented.
>
> http://www.ngdc.noaa.gov/mgg/image/charity.jpg
>
> http://www.ngdc.noaa.gov/mgg/image/Charity3d.jpg

I couldn't find anything in GEOREF about this feature.

Using Google, I found:

Holcombe, T. L. J. S. Warren, D. F. Reid, W. T. Virden
and D. L. Divins (2001) Small rimmed depression in Lake
Ontario: an impact crater? Journal of Great Lakes
Research. vol. 27, no. 4, pp. 510-517. online at:

http://cgrg.geog.uvic.ca/abstracts/HolcombeSmallDetailed.html

and

http://www.iaglr.org/jglr/jglr2704.html

The abstract in part reads:

"Bedrock consists of middle Ordovician limestones
100-150 m thick overlying rocks of Precambrian age.
The limited information available suggests that the
feature may be an extraterrestrial impact crater,
but other origins such as sinkhole, volcanic cone,
or kettle, are not ruled out. Time of formation is
not known, but likely times include the Pleistocene
when the area was exposed by glacial erosion, the
middle Ordovician near the time of deposition of
limestones, or the Cambro-Ordovician or Precambrian
when erosion surfaces of this age were exposed. A
subtle negative magnetic anomaly coincides with the
feature and is consistent with an impact origin,
though not positively diagnostic."

Another web page is"

"December 29, 1999 Possible Meteorite Impact Site
in Lake Ontario" at:

http://www.iaglr.org/hot/findings.html

and a figure at:

http://www.iaglr.org/pics/impact.gif

Other URLs are:

1. "NOAA RELEASES NEW POSTER OF FLOOR OF LAKE
ONTARIO" at:

http://www.publicaffairs.noaa.gov/releases2000/jan00/noaa00r301.html

"In addition, a small circular depression coincides with
the feature referred to as Charity Shoal. Although the
origin of the feature remains unknown, it bears a
"striking" resemblance to a simple impact crater."

2" GLERL 2000 Milestone Reports" at:

http://www.glerl.noaa.gov/res/Milestone/2000/Q1/2000q1reid.html

"A small circular depression (1000m in diameter, 15-20m
relief) with a continuous encircling rim coincides with
the feature referred to on nautical charts as Charity
Shoal. The origin of the feature remains unproven, but
it bears close resemblance to, and characteristics of,
a simple impact crater. The Canadian Geologic Survey
plans to sample the bottom rocks surrounding the feature
during the summer of 2000 in search of direct evidence
that it is of meteoric origin"

The only other reference to impacr crater associated with
Lake Ontario, I could find are:

Clark, J. F., 1970, An astrobleme in Muskoka District,
Ontario? Meteoritics. vol. 5, no. 4, pp. 188-189.

Waddington, E. D., and M. R. Dence (1979a) Skeleton
Lake, Ontario; evidence for a Paleozoic impact crater.
Canadian Journal of Earth Sciences. vol. 16, no. 2,
pp. 256-263.

Waddington, E. D., and M. R. Dence (1979b) Erratum;
Skeleton Lake, Ontario; evidence for a Paleozoic impact
crater. Canadian Journal of Earth Sciences. vol. 16
no. 6, p. 1297.

It has nothing to do with the Charity Shoal feature.

Skeleton Lake is found on a list that stated:

"It is most likely that most of these are not impact
structures."

In "List of probable and possible impact structures of
the World" at:

http://www.netppl.fi/~jarmom/geo/imp/possible.htm

Yours,

Keith'
New Orleans, LA
Received on Mon 16 Sep 2002 08:20:20 PM PDT