Geologist Kirt Kempter leads his final series into the geology of Western National Parks for 2023, with an in-depth look at one or more locations every month. Each program’s content is enhanced by geologic maps, photos, and Google Earth flyovers to reinforce geologic concepts and interpretations.
October 2 Glacier, Montana
The geologic processes that formed the mountains of Glacier National Park, established in 1910, represent a plate tectonic collision more than 40 million years in the making that spelled the retreat and demise of the great Western Interior Seaway. They are mostly composed of ancient sedimentary rocks dating back nearly 1.4 billion years. Fast-forward to the past two million, and Pleistocene glaciation has sculpted the dramatic alpine scenery we appreciate today.
November 6 Arches and Canyonlands, Utah
Arches and Canyonlands, two National Park neighbors in southeastern Utah, share a deep geologic connection along with their stunning desert landscape scenery. The star geologic formation at Arches is the Entrada sandstone, deposited by vast sand dunes during the Jurassic period. More than 2000 arches are found in within the park today, along with sandstone fins, balanced rocks, and pinnacles. The Colorado River, which flows along the southeastern boundary of Arches, then crosses into Canyonlands, where it makes a dramatic confluence with the Green River flowing south from Wyoming. Older rock strata from the Paleozoic Era are exposed in Canyonlands, forming dramatic canyons, cliffs, pinnacles, and bizarre formations.
December 4 Capitol Reef, Utah
Capitol Reef, established as a National Park in 1971, follows the axis of a geologic feature called the Waterpocket Fold, where folded geologic strata create a rocky spine for almost 100 miles. Geologic strata from the Mesozoic Era are the star attractions within the park, including the massive Navajo sandstone from the Early Jurassic Period. Erosion of this formation to create white-to-beige sandstone domes, reminiscent of the United States Capitol, give the park its name. The Waterpocket Fold has long presented a north–south barrier for human travelers, and few roads even today cross from west to east. The park includes canyons, cliffs, and arches, and the Freemont River has carved a splendid cross-section through the northern portion of the fold.