[BR-Crater] article on breccia/fractured rock boundary at Upper High Dry

[Ian Kluft]

I've changed the format of the Black Rock Crater web page so that it
shows updates by date.  The original article is still there, earliest
on the list and in a sidebar.
   http://ian.kluft.com/blackrock/impact-crater/

A newly-added article (with today's date) is "Breccia/fractured rock
boundary at Upper High Dry".  It explains some of our most significant
findings from last Summer.  I wanted to get this posted before we begin
this year's dry (exploration) season.
   http://ian.kluft.com/blackrock/impact-crater/2007-boundary-bafb.html

We've said most of this on the mail list.  But this puts it together in
one article where people can see we really did make a lot of progress
last Summer.

One of the things you'll see in the article is that I was told by
geologists who are experiences with impact craters (Bob and Charlie,
both subscribed to this list) that they'd want to at least hear of
breccia being found at a suspected impact site, in order to take it
seriously.  I knew there was some from photos of previous visits.
But once we started looking for it specifically, I realized that we
didn't have any idea how much there is.  There are mountains of
breccia, or at least the tops of the mountains consisting of breccia,
surruounding Upper High Dry.

An obvious thing we should find at a crater based on the diagrams of a
typical complex impact crater is breccia overlying fractured rocks.
Basically, those would represent the target rocks (the rocks which were
there originally, which got smacked) and the broken rocks which landed
on them afterward.  And we did find that.  There's a recurring boundary
of breccia above and fractured rocks below on the ridges north and
southwest of Upper High Dry lakebed.

So hopefully everyone understands why we were encouraged by last Summer's
findings.  We have more places to look for clues about an impact.  And
based on what we found so far, I have some ideas where I want to look
next for shatter cones too.