[BR-Crater] [Trackers] trip report and pictures from Crater Assault 3

[Brad Douglas]

---------- Original Message ----------------------------------
From: Ian Kluft <ikluft at thunder.sbay.org>
Date:  Tue, 9 Sep 2008 15:49:24 -0700

>Some geology terms used below...
>* breccia: broken, jumbled rocks re-cemented back together into a new rock
>* dike: a vertical flow up or down a crack with lava, impact melt or
>  crushed rocks that eventually turn to rock in the crack.
>* jointing: a long straight crack sort of like a mini-fault, no debris in it

No sills? :-)

>Summary of the trip
>-------------------
>
>One very important finding from this is the widespread area with the
>thinly-sliced fractured rocks.  Bob pointed out there is also jointing
>in parallel mini-fault-like straight cracks across the fracturing.
>That indicates the fracturing is from a source of stress, not from
>cooling.  And it isn't a fault zone.  We found these kinds of rocks
>at Upper High Dry and locations a couple miles north, south and west
>so far.  (I had to check the photos from Stratofox 4 last year to
>confirm it's also to the south.  We didn't go there this time.)

Again, the "thinly sliced" rocks are neither from volcanic cooling nor impact.  They are created by successive freezing and thawing, which is often extreme in NV:
http://commons.wikimedia.org/wiki/Image:Weathering_freeze_thaw_action_iceland.jpg

 




________________________________________________________________
Sent via the WebMail system at touchofmadness.com