caldera

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It was time to close the day. I left McDermitt, Nevada, after sharing results of recent projects in a long meeting with the council of the Paiute-Shoshone Tribe. Archaeological studies driven by proposed developments are not always welcomed, and while the meetings are almost always cordial and informative, they can be emotional and contentious given the variety of views regarding the impacts, good and bad, that projects bring. I do my best to be honest and clear in my presentations, but I understand that I work for a project proponent (utility or mining companies, for example) at the behest of a government agency, and sometimes limited by my western scientific perspective, I fail to resolve and answer adequately the deeper concerns of some members of the traditional community. We could do better. Weary from the long meeting, I pointed my rig into the hills west of Quinn River Valley, breathing easier and settling into the fading light of the afternoon.

Reveling in the sound of dirt under my tires, my head cleared; a pronghorn antelope stared at my intrusion. The volcanic tablelands of the Sentinel Hills spread to the southern horizon, and I could see Hoppin Peak rising as a rim-rocked butte, which I knew overlooked the Quinn River Valley now to my east. I would camp up here in the sagebrush and cheatgrass but, first, I thought I had enough evening light to walk a few miles to the Hoppin Peak high point. Finding a level area to eventually pitch my tent, I grabbed my pack and set off.

The Sentinel Hills are block-faulted remnants of lava flows that oozed from the volcano that would eventually collapse to form the McDermitt caldera. Prior to its collapse, the volcano extruded a prodigious amount of rhyolitic tuff and lava. The eruption produced deep beds of pyroclastic ash with unimaginably hot and dense ground-clouds transitioning to highly viscous lavas; these may have cycled over and over as eruption followed eruption during the fiery event. In places, the weight of the viscous beds (along with somewhat unique combinations of chemistry and water content) resulted in strata of thick, glassy ignimbrite beds and, sometimes, massive glass beds of obsidian were left behind. These processes, especially the extensive evacuation of so much volcanic material, resulted in the volcano’s collapse by about 17 million years ago, leaving a mark on northern Nevada that remains to this day – and leaving a vast toolstone resource so prominent in the regional archaeological record. I have spent considerable time in the hills of the caldera but have yet to visit the high point on its eastern margin.

The day’s light faded as it bounced among building clouds. I walked the rolling hills skirting the tops of canyons that cut into the volcanic rocks. Obsidian seems absent on the top of the tablelands, as I continue to map the geography of the volcanic glass around the caldera. It is not a demanding walk, the only challenge coming from two groups of wild horses that cannot decide if I should be there. They are at once curious and then immediately skittish, and I only want to stay out of harm’s way. The horses are momentarily fascinating and beautiful, bristling at my presence, but their numbers take a toll on the springs, and the local slopes are cut by numerous trails that radiate between water sources, most of which are now dry.

In a last gasp, the light rakes beneath the clouds as the sun sets about the time I gain the rimrock and talus that guard the summit. There is a small rock cairn and the usual quiet register. I had hoped for a dramatic sky highlighted above the setting sun, but the clouds dropped in a broad western curtain, and dark began to set in. I had several groups of horses to navigate through, so I did not wait any longer.

I had, of course, packed my headlamp, but I prefer not to use it unless completely necessary. I could hear the horses shuffling nearby, but they kept their distance as I made my way back to the truck to set up camp. Hoppin Peak is not dramatic in any way, but the walk is refreshing, and I feel much better for it. I learned something about the lavas of the Sentinel Hills, confirming that obsidian nodules of toolstone quality (or any really) are absent from the tops of the flows. I can expand my maps a bit more, adding this detail to the eastern margin of the caldera. I will continue my caldera excursion tomorrow after listening to the Chukar and coyotes; a Common Poorwill sings its haunting, lonely notes somewhere in the canyon below. A quiet close to a long day — the small hills almost always provide that.

Keep going.

Please respect the natural and cultural resources of our public lands.

#naturefirst #keepgoing