June 2 – June 5, 2020.
John C. Fremont called it the “Great Basin” in 1844.
His father-in-law, Missouri Senator Thomas Benton, had gotten him the job. In May 1843 Fremont led a party of 39 men west on the Oregon Trail. Reaching what is now Nevada, they turned south to explore and map. They determined that no river crossed the Sierra Madre mountains. The precipitation that landed in Nevada stayed there. No rivers ran to the sea. Nevada was basically a great basin.
The western deserts are all about elevation and moisture. The Saguaran and Chihuahuan deserts are mostly low elevation. They are covered with cacti, which require minimal moisture. Sagebrush replaces cacti in the northern high deserts, which get more moisture.
Throughout the deserts, high mountains get the most precipitation. Junipers, then oaks appear above the desert, giving way to Ponderosa pines high on the mountains. Above the Ponderosas ancient pinyon pines can be found. Above that, the trees disappear altogether. Cools temps keep snowfall from melting away. And if it stays frozen all year you might find a glacier!
I guess we shouldn’t have been surprised to see a glacier in the Great Basin, but we were. I am so glad that we did. We have seen the effects of erosion everywhere out west. We’ve seen huge canyons, with relatively small rivers in them. Even though we know the deserts were wetter in the past and that water flow increases with summer storms, it’s still hard to imagine these trickles of water cutting away so much rock.
Cue the glaciers! Not only was it wetter here in the past, it was also colder. There were more glaciers, and these guys are the steamrollers of erosion. The underside of a glacier is ice wrapped around rocks. As the heavy sheet of ice moves downhill it brings the rough base with it, grinding everything in its path. To me, it seems more like sanding with 40-grit sandpaper than using a thin, weak stream of water.
This was our first glacier. Hopefully, we’ll see more.