Canyonlands

A short, easy trail leads to a low arch set right at the lip of the mesa. What makes it a first stop for reading the rock is not the arch itself but what it frames: through the opening the land falls away in a series of flat steps, each a different layer of stone, dropping toward the canyon floor and the mountains beyond. You are standing on the youngest rock, the top of the pile; everything you see through the window is older, and it gets older the farther down your eye travels. The layers lie almost dead flat, stacked like boards, because nothing has tilted or folded them since they were laid down. That flatness is the whole trick of this place — it lets you read the stack in order, top to bottom, without a geologist to sort it out. The arch is a thin lip of sandstone worn through where water collects and freezes in a shallow basin; it will widen and one day fall, the same slow work going on across the whole park. Come at first light if you can, when the low sun throws the far cliffs into relief and every separate layer stands out as its own band of shadow and color.

From this railing at the mesa’s western edge you look down onto a broad pale bench far below, and beyond it the Green River winding through its own deeper canyon. The overlook is worth the short walk because it lays the layered stack out sideways for you, like a diagram. Near your feet is the top of the pile; a long way down, that flat pale shelf is a single hard layer of sandstone that the softer rock above has worn back from, leaving it standing out as a bench; below that, the river has cut on down through still older rock to reach where it flows today. Each level is a different age, and because the desert grows so little here — thin soil, scattered shrubs, bare stone everywhere between — nothing hides the boundaries between them. You can trace one layer for miles along the canyon wall, a continuous line, and know it was all laid down as one flat sheet before the rivers went to work. A geologist’s field report was written from this exact overlook; you are reading the same page they read.

A steeper trail climbs onto Aztec Butte, a rounded dome of pale rock standing above the mesa. Up close the stone tells you exactly what it used to be. Look at the long, sweeping curves banded through it — sets of slanting lines that arc and cut across one another. Those are the faces of sand dunes, frozen in place. In Jurassic times, roughly a hundred and seventy million years ago, this whole country was a desert of wind-driven dunes, a sea of sand spread across much of the region. The wind piled the sand into ridges, and the slanting layers are the old dune faces, buried, pressed, and cemented into solid rock without ever losing their shape. The dome’s rounded knobs and the checkered grooves weathering across them are the signature of this particular layer wherever it surfaces in the park. It is one page of the book you can walk up to and lay your hand on. Standing here on hardened dunes, with the flat-lying younger rock stripped away around you, you get the plainest lesson the park offers: solid stone was once as loose and restless as a windblown beach.

Far below the mesa rim runs a broad, pale bench of rock, and along its top threads a rough unpaved road — the White Rim Road, named for the layer it follows. That pale shelf is a single hard band of sandstone, tougher than the softer rock above and below it, so it stands out all the way around the Island in the Sky as a continuous ledge, a stair-step partway down the canyon walls. It is one of the clearest single layers in the whole stack: you can pick it out from almost any overlook on the mesa as one unbroken line circling the canyons below. The road itself carries a harder history. It was cut in the 1950s by the Atomic Energy Commission so prospectors could search this rock for uranium to feed Cold War weapons. The deposits proved thin, the mines produced little, and they were abandoned; the road they left behind is now the way down into the layered country for those with a rugged vehicle or a bicycle and several days. From above, though, you need none of that — the layer it rides is plain to read straight from the rim.

Out toward the western edge of the mesa country stands Muffin Butte, a small flat-topped summit looking down over Soda Springs Basin and, beyond it, the Green River. It is a remote perch, well off the paved road and reached only by long backcountry travel, and it earns the effort by showing you the other half of the story. The overlooks along the rim show you the flat layers, stacked and waiting; from a place like this you see the tool that opened them. The Green River, joined not far off by the Colorado, has spent an immense stretch of time cutting down through the whole stack, carrying the loosened rock away grain by grain and leaving these canyons behind. Soda Springs Basin below is a wide bowl the river’s tributaries have hollowed out of the softer layers. Stand here and hold both ideas at once: the land was built upward, flat sheet on flat sheet, over hundreds of millions of years, and then the rivers took the same long patience to carve back down through it. The book was written from the bottom up and is being read from the top down.