Friday, February 28, 2014

Geo 730: Feb. 28, Day 424: The View West

A classic Basin and Range scene, this was the view across Guano Valley from our stop on Doherty Grade. The far side of the basin appears to be a series of small scarps, as opposed to one large one, as here on the east margin. The light deposits on the valley floor are a bit of a puzzle; I have long assumed they're simply salt. They may be, but thinking more carefully about it, I think that might be "salt" in the broader chemical sense rather than the typical colloquial NaCl sense. I don't think the shrubs would be as pervasive if these white deposits were, say, halite (the mineral name for NaCl). They might be carbonates- calcite, aragonite or dolomite, for example, or sulfates, such as gypsum. On the other hand, they might be simply the lightest and finest clays, and not salt deposits of any kind. However, the strong correlation between fewer shrubs and lighter ground suggests to me that the concentrations of salt are probably higher in the light areas.

Photo unmodified. August 19, 2011. FlashEarth Location.

1 comment:

SkinnyDennis said...

Hi Lockwood. Longtime daily reader.

Wondered about the geology of the area and found this "GEM" report made in 1983.