6979 ft (2127m) — 1510 ft gain
Although I had been able to visit the Cuprite Hills on the journey south, fieldwork along the Gila Mountains of southern Arizona postponed our Second Friday overland recce for March. To keep our run going, however, we took to northwestern Nevada on the fourth Friday – close enough. We traveled north, skirting the Black Rock Desert, to check conditions for spring-time fieldwork along the Buckhorn Road above Duck Flat. To our surprise, we found that winter snow-cover prevailed at the road’s summit and decided not track up the road; plus, when saturated these volcanic lithosols become soul-sucking clay when saturated, so the better part of valor is to wait a few weeks for drier conditions. We would work on my obsidian mapping project, traverse the Cottonwood Creek Caldera, and head toward Mahogany Mountain – Rowland Mountain along the Buckhorn Road would still be there later this year.
A dramatic series of volcanic eruptions in the Miocene of northwestern Nevada, 16 to 13 million years ago, give or take, drenched the landscape with rhyolitic and basaltic lava. The driving force behind these cataclysmic events was the same magma plume that drive today’s geyser of Yellowstone. Some of the eruptions produced expansive pumice-like tuffs, many welded to solid rock, and, along with this, came extrusions of quick-cooling, glassy obsidian. The eruptions left vast calderas, with obsidian seams along margins and slopes; these filled with vast lakes as the volcanos’ hollowed centers collapsed. Cut by rivers and warped by mountain building, the calderas were deformed and can be hard to recognize today. However, the obsidian, lake sediments, and broken lava flows remain. Because obsidian is an important native toolstone, archaeologists are interested in its natural distribution because it provides significant clues to the movement, conveyance, and trade of the darkly colored glass so useful for making tools. I have long focused on studying and adding to the maps of the calderas and the obsidians they hold.
But those are stories better told elsewhere. Tonight, we are climbing through a series of rhyolitic lava flows to the rounded dome of Mahogany Mountain, the high point of the Little High Rock Mountains. We had traversed an old two track until a spring-bog stopped us. This was fine, we were less than a mile from the wilderness boundary and, because this is not a high mountain, we needed some distance to get some elevation. Intersecting another two-track, now hiking along the wilderness area, we eventually turned up a small canyon, heading cross-country up easy slopes.
Wild horses watch from scattered groups as we follow their numerous trails between a set of rimrocks and then climb through the boulders of the summit dome. To our surprise we hit an old fenceline, probably an early grazing allotment that we have to climb over to get to the little summit cairn holding the register. It is not a popular climb but the views into the High Rock Country are magnificent. Off the north edge, a ragged stand of mountain mahogany trees gives credence to the little mountain’s name.
It is a cloudless sky, so the sunset comes quick, and we are soon walking anastomosing trails through golden bunch grasses, which seem not quite ready for spring. Our photography is simple and documentary, though a rising full moon provides early drama to the evening sky. In the dark, we gain the road and enjoy the walk as the brightest stars appear; the flagrant moon will keep the others at bay.
We skottle-up a post-climb feast back at camp. The moon lights up our little perch on the edge of the Cottonwood Caldera, fitting closure to our walk in the flows of the volcano’s edge.