[BR-Crater] photos from Stratofox 4 trip to Black Rock

[Ian Kluft]

I posted my photos of this past weekend's Stratofox 4 trip to Black Rock at
   http://www.stratofox.org/pics/sf4-200708/
As Brad, Rafael and Heather post their picutres, I'll add links to them too.

I separated out the pictures of rocks from the general camping trip
because each appeals to different audiences.
   general: http://www.stratofox.org/pics/sf4-200708/ian/
   rocks:   http://www.stratofox.org/pics/sf4-200708/ian/rocks/
   
As with previous visits to look for crater evidence at Black Rock, we've
found new data that moves us forward.  It's very encouraging.

We didn't come back with boxloads of textbook-quality shatter cones.
But we found some rocks with possible shatter cones of less than
textbook quality.  We need to look at these photos, have some
discussion and get some expert opinions.

A number of rocks got our attention as having possible shatter cone patterns.
With some irony, after a lot of hiking, the most promising looking rock was
right in the 4x4 trail where we parked.  A rock inclusion in a breccia rock
had what looks like shatter cones including concave cones.
   http://www.stratofox.org/pics/sf4-200708/ian/rocks/img_9996.jpg
The rock was too hard to break off a piece with a rock pick.  We tried.

One thing we learned is the "thinly-sliced" fractured rocks (which are
relatively easy to find in rocks below the melt/breccia layers) in the
area were always nearby wherever we found rocks with very thin fractures
that resembled the striations of shatter cones.  These were usually only
accessible where streams and gullies cut through layers below the floor
of the melt/breccia layers that spread across the southern Black Rock
Range.  Otherwise much of the surface is covered by loose rocks.

Where the easier-to-find "thinly-sliced" fractured rocks were exposed,
they seemed to be an indicator of where to look nearby (wherever exposed
bedrock could be found among the loose cover) for even thinner fracture
patterns.  An example:
   http://www.stratofox.org/pics/sf4-200708/ian/rocks/img_9954.jpg

In those places we found some loose rocks with textures that resembled
shatter cones.  Examples:
   http://www.stratofox.org/pics/sf4-200708/ian/rocks/img_9986.jpg
   http://www.stratofox.org/pics/sf4-200708/ian/rocks/img_9987.jpg
   http://www.stratofox.org/pics/sf4-200708/ian/rocks/img_9988.jpg
   http://www.stratofox.org/pics/sf4-200708/ian/rocks/img_9990.jpg

It's a big area.  There are still many many more places to search.
Let's figure out what we've learned from this trip first.