[BR-Crater] submitted impact database update

[Ian Kluft]

I submitted the update to David Rajmon, maintainer of the "Impact Database",
formerly known as the Suspected Earth Impact Sites (SEIS) list for the Impact
Field Studies Group (IFSG).  His new web site is at http://impacts.rajmon.cz/

----- Forwarded message from Ian Kluft <ikluft at thunder.sbay.org> -----
Date: Wed, 12 Aug 2009 23:35:31 -0700
From: Ian Kluft <ikluft at thunder.sbay.org>
To: David Rajmon <drajmon at yahoo.com>
Cc: Bob Verish <bolidechaser at yahoo.com>
Subject: impact database update for Black Rock

I have an update for the entry for Black Rock on your impact database.

In our research of the Black Rock area, the previous 48x64km ellipse theory
has been superseded by an 87km circle centered at 40.90 N 118.94 W.

This project is at the same URL as before:
   http://ian.kluft.com/blackrock/impact-crater/

There is a possible/apparent remnant of a concentric inner ring, which was
the source of the confusion that led to the earlier ellipse theory.  But
once the circle was found, the ellipse quickly fell out of favor.  So far
everyone who has looked over the circular outline says they're a lot more
comfortable with it than with the previous ellipse theory, myself included.

We have additional observations from the rocks since the last submission.
The Black Rock Range has been observed to have a persistent pattern of
hundreds of feet of breccia overlying fractured and jointed rocks across
an area of several square miles that we observed.

Bob Verish visited the area briefly on a camping trip in Sept 2008.  With
the available time we decided to make it an informal introductory tour for
him.  He said the jointing in the lower rocks (below the breccia) appeared
to indicate they have been subjected to significant stress and not from
faulting.  He also took an interest to some nearby structures which looked
like volcanic necks near 41.0000N 119.0000W, where the USGS geologic map
says it's basalt.  We found the apparent necks are entirely made of breccia.
The color looked enough like basalt at a distance, but not up close.  There
was no basalt to be found anywhere.  Bob commented that the USGS maps of
that area seemed to have been made too hastily and needed to be reviewed.

----- End forwarded message -----