A nice little photo "what is it?" for the day. The dark chunks are about a foot across and the location is at the south end of Joshua Tree National Park. I was going through the photo archives of one of my meetings of the National Association of Geoscience Teachers, preparing a post about our roadguide for the geology of the Coachella Valley and surrounding mountains. You can check it out here.Thursday, May 7, 2009
A Whatizit? Photo for the Day
A nice little photo "what is it?" for the day. The dark chunks are about a foot across and the location is at the south end of Joshua Tree National Park. I was going through the photo archives of one of my meetings of the National Association of Geoscience Teachers, preparing a post about our roadguide for the geology of the Coachella Valley and surrounding mountains. You can check it out here.
Xenoliths differentially weathering out of a granite?
ReplyDeleteIronstone rip-ups differentially weathering out of a massive, coarse-grained (possibly arkosic??) channel sandstone?
ReplyDelete--Howard (Calgary, AB)
My guess is a series of xenoliths
ReplyDeleteThanks, yes, these are xenoliths of metamorphic rock that have eroded in a somewhat unusual fashion from granite rock. The answer about arkose reminds me of my first field geology class; our prof took us to a site in Cajon Pass without establishing the context, and stuck us in front of an outcrop and asked what it was. We all agreed that it was an exposure of arkosic sandstone, only to find out that it was highly weathered granite.
ReplyDeleteIn my imagination,but not in stated in geological terms it looks like an extreme close-up of a chocolate chip cookie with very large chunks of blocky and mouthwatering chocolate emerging from the cookie dough...sorry, I couldn't resist :)
ReplyDeleteIt *does* look a bit like a closeup of chocolate chip cookie dough. Mmm...
ReplyDelete