Thursday, February 20, 2014

Geo 730: Feb. 20, Day 416: Hart Mountain and Warner Valley

(Right-click image here for size options) I just spent 20 minutes or so tracking down the name of the escarpment on the left (west)... given the name of the basin is Warner Valley, I shouldn't have been as surprised as I was that the name of that rim is Warner Mountain. In this part of the valley, it's fault-bounded on both sides. To the north, Hart Mountain, in the right center, continues as Poker Jim Ridge/Rim for quite some distance. However, Warner Mountain dips down to the north, so by the time you get to the sunstone area, maybe 40 or 50 miles north of this spot, the west side of the valley consists of low hills. Hart Mountain is capped by Steens Basalt, which in certain flows, has enormous phenocrysts of plagioclase. It's those phenocrysts, weathered out, and I suspect making an aeolian lag, that make up the sunstones in BLM collecting area.

Two other features about the Hart Mountain/Plush area that are noteworthy: The wildlife refuge to the north of the town on the mountain's west flank is a spectacular birding area, and the refuge atop the mountain has more often than not provided pronghorn sightings. They tend to be shy, but keep an eye on hillsides and ridgelines in the mid-distance. If you're lucky, they'll try to race your vehicle! The other is a very nice hot spring, here, right up near the top of the peak.

This basin was the site of a deep pluvial lake during the Pleistocene. I can't pick them out at this scale, but if you look at the full-size image, one can see numerous benches and horizontal lineations of trees along both sides of the valley. These mark pluvial shorelines.

Photo stitched in HugIn. August 19, 2011. FlashEarth Location.

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