Basin and Range

Twelve million years ago the Earth’s mantle started stretching North America, pulling its western edge into the Pacific; splitting the western part of the continent into strips that ran north-south; creating, then widening, the cracks between those strips of continent.  The cracks became gaps and the long crustal blocks lost their equilibria.  They tipped, some dipping their western edges into the Earth’s viscous mantle and hoisting their eastern edges skyward; some tipping the opposite way.  The result was a serrated landscape.  Long-north south valleys where crustal edges sank into the mantle, then high north-south mountain ranges where crustal edges were thrust upward.  Basin and range.

The crust continues to stretch.  The cracking, splitting, and tilting moves ever eastward, having now reached what we call the Grand Tetons and the Wasatch Front.  Basin and range faulting long since passed eastern Nevada, where Duke and I sit like corks on the geologic ocean.  A traveler moving west from the Great Salt Lake crosses the Pilot Range, Pilot Creek Valley, the Toano Range, Goshute Valley, the Pequop Range, Independence Valley, the Spruce Mountian Ridge, Clover Valley, the Humboldt Range, Starr Valley.  On it goes.

Drainage is poor in North America’s basin and range, and precipitation scarce.  But over twelve million years, erosion has had its effect.  As the crustal gaps widen and the mountain ranges rise, daily winds and intermittent rainstorms flatten the mountaintops like strokes of sandpaper.  Dislodged rock and dirt move down the alpine slopes like sawdust falling to a carpenter’s floor, only to build up in the valleys because there is no river to carry the sediment away.  As the mountains rise and the valley floors fall, erosion levels the mountains and fills the valleys.  Geologists call the process "downwasting."  It is a battle that only erosion can win.

Tonight in Clover Valley, the basin and range is quiet.  Standing atop millions of years of sediment, I smell today’s sagebrush and feel tonight’s breeze, drifting cool and steady from the south.  Lights flicker at the base of the Humboldt Range.  These mountains were battling erosion well before the first of the ice ages that resculpted much of this continent, well before the Yellowstone supervolcano last spewed 600 cubic miles of rock into the atmosphere, and well before Homo sapiens sapiens evolved as a species.  In the context of these mountains, the time since man started living in sedentary communities capable of producing things like roads or fixed settlements was only a heartbeat ago.  The here and the now – the breeze, the sagebrush, the chill, the coyotes that just started yipping for the evening hunt – are ephemeral beyond comprehension.

I stuff my hands in my pockets.  The coyotes quiet down, and I listen to the distant sound of traffic along Highway 232.  The immensity of space and time dwarfs human history; overwhelms human understanding.  That could be intimidating.  But hell.  I’m just happy to be here.

Pilot Creek Valley.

Duke and me in the basin and range.  So far we have found the accomodations adequate.