[BR-Crater] overview of the Summer's observations at Black Rock (was: asteroid 1-in-75 chance...)

[Ian Kluft]

I was hoping to see some updates on the story about the asteroid 2007 WD5.
I scanned the news but found nothing new today.

I found the reason why we need to be a little patient.  The full moon is
in the way.  It mentions that in the original JPL press release...
   http://neo.jpl.nasa.gov/news/news151.html

So we'll wait.  Since we expect this could cause a flurry of discussion
about Earth impacts, I guess we need to finish posting the info we
collected about the theorized Black Rock crater soon.  Fortunately,
I have a short break over the holiday since I completed my training
and passed the flight exam to get my instrument rating on Friday.  I'll
try to fit the web site update in before I start on the next step in my
flight training.

A quick summary of our observations from Upper High Dry lakebed the Summer...
* We hiked around the north, southwest and east sides of Upper High Dry.
  We found some commonalities of the rock structures across the area.
* In the north and southwest sides, we found an extensive boundary in
  the rocks where there are thoroughly fractured rocks below, sometimes
  looking as thinly-sliced as deli cold cuts, except they're rocks.
  I gave those the obvious nickname of "thinly sliced" fractured rocks.
  The fracturing pattern so far appears pervasive across different kinds
  of rocks below the boaundary line.
* On the east side, we didn't make as extensive a search.  So far we've
  only found breccia on that side.  The trend looks like a lot of breccia
  in the mountains along the entire east side of Upper High Dry.
* Above the boundary, the rocks are all breccias.  (Jumbled rocks
  containing broken-up older rocks cemented together.)  Mountains of
  breccia.
* Brad looked at the breccias watchful for whether they contained jagged
  or smoothed clasts/inclusions.  Any smoothed rocks in the breccias
  would point to an erosion origin.  But so far everything has been
  jagged inclusions.
* All the red rocks I could find in the area, which had previously been
  presumed to be lava when viewed from a distance, are all breccias.
* Near and below the boundary line, there are frequent "breccia dikes"
  down into the fractured layer which appear to be filled from the
  breccia above.

So far none of that is proof of anything.  Some point out that volcanic
breccias can also contain jagged clasts.  But the combination of fractured
rocks below and breccias above are consistent with an impact scenario.

Bob V and Charlie W, geologists with impact experience, said that breccias
are the right thing to find to get interest of more geologists.  You'll see
it when I post annotated photos of the fractured-below and breccia-above
boundary at Upper High Dry.

Anyway, when we get a chance to show geologists around the area, this gives
us some good areas to start at.

BTW, the island in the Upper High Dry lakebed is, as you might expect,
part of the fractured-below area.  That's where I mistook the pervasive
fracturing for shatter cones at the beginning of the learning process
a year ago.