Traces of an ancient aquatic world in Capitol Reef photographed from the space station



Capitol Reef National Park in south-central Utah. May 2, 2022.

In the Utah desert, the red rocks, cliffs and canyons of this nautically named national park — and many of its famous fossils — owe their existence to water.

Capitol Reef National Park in south-central Utah is home to no capitol or reef. It was named instead for two geological features: the prominent white domes of Navajo Sandstone, which reminded early settlers of the Capitol building in Washington, D.C.; and a formidable ridge of rocky cliffs that presented a barrier to passing. The settlers (some probably traveling in prairie schooners) compared it to the hazard to marine navigation of an ocean reef.

The ridge, called the Waterpocket Fold, runs north to south for 140 kilometers. It can be seen in the image above, which was acquired on May 2, 2022 by Landsat 9’s Operational Land Imager-2 (OLI-2).

The ridge is named after a common feature of the park. Water pockets are natural depressions or pockets – eroded from rock – that collect rainwater and snowmelt, a valuable source of fresh water for humans and wildlife in the desert. Geologically, Waterpocket Fold is a monoclinal, a structure in which the rock layers have been folded up or down on one side. (Structures in which rock layers are bent on both sides—either curved like a U-shaped smile or downward like a frown—are called synclines and anticlines, respectively.)

Between 75 and 35 million years ago, the tectonic forces that uplifted the Rocky Mountains also deformed older rocks beneath Capitol Reef. The rock layers above did not break, but bent, like a tablecloth draped over the edge of a table. The curvature of this drape forms the Waterpocket Fold. More recently, rains, flash floods, and freeze-thaw cycles have eroded and carved the cliffs, canyons, bridges, and domes into what we see today.

Capitol Reef tells a geological history of hundreds of millions of years of deposition, uplift and erosion, punctuated by episodes of volcanism and glaciation. The park has an almost complete series of rock layers ranging from the end of the Permian (about 290 million years ago) to the end of the Mesozoic Era (66 million years ago). Deposited along and into a shallow sea and ancient delta, these rocks hold an almost continuous record of life and environments here from before the rise of the dinosaurs until their demise.

Today, they are some of the best-known rocks on the Colorado Plateau, including the Moenkopi, Chinle, Navajo, Entrada, and Dakota formations. Several of them can be seen in the image below from Great Thomson Mesa in Capitol Reef. The photograph was taken on June 14, 2009 by the crew of the International Space Station.

Great Thomson Mesa

Great Thomson Mesa. June 14, 2009.

Capitol Reef is also home to part of the largest and oldest fossil megatrack in North America. These are mainly trace fossils, or ichnofossils, found in the Moenkopi formation, which formed in the early Trias Period, about 240 million years ago. Unlike body fossils, trace fossils are the marks or other evidence that ancient life left behind, such as footprints, burrows, and even feces (coprolites). Many Capitol Reef tracks have formed when fish drag their fins or reptiles scratch their feet, toes, or claws as they swim along an ancient shoreline or cross a tidal mudflat. The footprints they left were then filled with sand, which hardened into sandstone, forming casts.

In May 2022, park officials reported the loss of part of a rare fossil pathway. After posting a photo of a rocky outcrop on social media, park officials were alerted to the missing tracks by a paleontologist familiar with the site. A review of previous site photos revealed the the fossils had been removed between August 2017 and August 2018.

" data-gt-translate-attributes="[{" attribute="">Nasa Earth Observatory image by Lauren Dauphin, using Landsat data from the US Geological Survey. Photograph of astronaut ISS020-E-9861 was acquired on June 14, 2009, with a Nikon D3 digital camera fitted with an 800mm lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. Image was taken by the Expedition 20 crew. The image in this article has been cropped and enhanced for improved contrast. Lens artifacts have been removed. The International Space Station program supports the lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet.


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