Monday, June 18, 2012

The Misty Mountains

Four weeks ago, we were driving west over Emigrant Pass on I-80 on our 2nd, and final, U-Haul van trip, when I noticed (I was in my newish jeep, and MOH was in the U-Haul) that the mountains and valleys of the northern Basin and Range were rapidly becoming obscurred by dust.
In this first shot looking southwesterly from a relatively obscure point on Bobs Flat, down Bob Creek toward the Horseshoe Ranch near Beowawe, NV, our view has been dusted, making the visible hills and mountains appear vague, as if lost in a morning mist. The prominent hill in the central part of the photo is a subrange of the northern Shoshone Range, and the cliffy north-facing side of the subrange is officially known as Malpais, but is usually called the Malpais Rim.

The Malpais Rim, site of The Geysers near Beowawe, NV, — the geysers are, sadly, no longer geysing — is "one of several east-northeast-striking, fault-bounded cuestas in north central Nevada" (Eric Struhsacker, 1980). In the photo, the north-northwest facing scarp of the Malpais Rim is facing just a little away from us toward Whirlwind Valley, the flat area on the right side of the photo. Beyond Whirlwind Valley, a farther part of the northern Shoshone Range has an unusually vague outline. We can't see the Cortez Mountains in this dusty view; they are usually visible beyond the Malpais Rim.
Here's our general location (map and link from The National Map, courtesy U.S. Geological Survey). [Btw, all the maps shown here will look better when enlarged by clicking; maps from The National Map can be explored more fully by following the link provided.] Carlin is near the east edge of the map, just west of the U.S. 40 loop through Carlin Canyon (this fairly ancient AMS sheet for the area shows I-80 as partially built, and Highway 40 still in existence before the completion of the Carlin tunnels). Battle Mountain is not far off the west edge of the map.
Zooming in somewhat (map courtesy U.S.G.S. but downloaded from a different part of their website, we can see Bobs Flat, the flat area in the upper center of the map (Highway 40, rather than I-80, is shown on this old 15-minute map), and Beowawe, the tiny town, ghost town, and ranch area on S.R. 306 in the lower left of the map.
Zooming in even farther, we can now finally see the area of The Geysers and the Malpais Rim (The National Map link). I've outlined Beowawe and The Geysers in dark cyan.
A little farther down the west side of Emigrant Pass on the descent toward the Beowawe Rest Stop — which used to be a great place to see The Geysers before their feeder geothermal exploration wellheads were plugged for geothermal production — we see two subparallel slopes comining southeastward off the Argenta Rim in the northern Shoshone Range, in front of the closer and clearer hills east of Whirlwind Valley. These closer, unnamed hills — irregularly north trending — sit between Bobs Flat and the northeast end of Whirlwind Valley.
The Argenta Rim (skewed rectangle) is another east-northeast-trending subrange of the northern Shoshone Range, similar to the Malpais Rim (The National Map link).
Coming into Battle Mountain, I grabbed this shot of the north end of the Shoshone Range near the Betty O'Neal mine in the Lewis silver mining district, in hopes of showing an alluvial fan slope coming off the mountains toward the Reese River Valley, but that slope is barely visible in this grainy, overprocessed photo. Nevertheless, you see the dusty conditions. This dust, and the dust we first saw coming over Emigrant Pass, is coming all the way from the Carson and Humboldt Sinks, located about 100 miles southwest of Battle Mountain and about 120 miles southwest of Emigrant Pass.
Coming around the usually blustery turn at Button Point, I had this view of the southern part of the Santa Rosa Range, with Bloody Run Peak being the high point on the left (south). The high part of the Santa Rosa Range — to the north, and off the photo stage right — was being thoroughly dusted by winds coming off the Black Rock Desert, and was not visible from I-80.

Our next view to the west, of Winnemucca Mountain, meant our second and last U-Haul trip was nearing an end, except for the unloading that took one more day — and except for the unpacking that is still in progress. A few views from Winnemucca Mountain, including one of Bloody Run Peak, can be seen here.

Selected Reference:
Struhsacker, E.M., 1980, The geology of the Beowawe geothermal system, Eureka and Lander Counties, Nevada: University of Utah Research Institute, Rept. ESL-37, 78 p.

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