Posts

POTD January 10, 2014: Jurassic-age Navajo Sandstone, Grand County, Utah

Jurassic-age Navajo Sandstone, Grand County, Utah
Photographer: Kent Brown

Arches in the making (alcoves) in massive cliffs of Jurassic-age Navajo Sandstone, near Moab, Grand County.

 

POTD December 30, 2013: La Sal Mountains, Grand and San Juan Counties, Utah

La Sal Mountains, Grand and San Juan Counties, Utah
Photographer: Jay Hill

The La Sal Mountains, near Moab in southeastern Utah, are laccoliths formed when upwelling magma intruded into and bulged the overlying sedimentary rock layers upward. The magma did not reach the surface, but subsequent erosion of the softer sedimentary rocks exposed the peak-forming igneous rocks that rise above the surrounding landscape.

POTD December 13, 2013: The Windows Section, Arches National Park, Grand County, Utah

The Windows Section, Arches National Park, Grand County, Utah
Photographer: Nicholas Daniels

North Window Arch frames the distant landscape through a fin of the Jurassic-age Entrada Sandstone. The Windows Section, Arches National Park, Grand County.

POTD August 27, 2013: Dinosaur Tracks near Moab, Grand County, Utah

Near Moab, Grand County, Utah
Photographer: Carole McCalla

During Jurassic time, a sauropod walked across mud, sinking deeply into it. The footprints can be seen preserved in the rock near Moab in Grand County. BLM interpretive site.

POTD August 23, 2013: Poison Strip area, east of Arches National Park, Grand County, Utah

Poison Strip area, east of Arches National Park, Grand County, Utah
Photographer: Don DeBlieux

A geologist examines a sequence of Early Cretaceous-aged paleosols (ancient soils) in the Yellow Cat Member of the Cedar Mountain Formation. Many dinosaur fossils are found in these rocks, and the study of paleosols can provide valuable
information about the environments in which these dinosaurs lived.

POTD August 9, 2013: Wall Arch, Arches National Park, Grand County, Utah


Wall Arch, Arches National Park, Grand County, Utah

Photographers: Grant Willis (top)
and Rich Giraud (bottom)

Now you see it, now you don’t. Formerly located along the Devils Garden Trail in Arches National Park, Wall Arch collapsed sometime during the night of August 4th, 2008.

POTD August 8, 2013: Delicate Arch, Arches National Park, Grand County, Utah

Arches National Park, Grand County, Utah
Photographer: Michael Vanden Berg

A small window in the Slick Rock Member of the Entrada Sandstone frames a view of Utah’s most famous landform, Delicate Arch. The arch is composed of Jurassic-aged sandstone including the Slick Rock Member (base and  pedestals) and Moab Member of the Curtis Formation (bridge). In the distance, Oligocene-aged igneous rock forms the snow-covered La Sal Mountains.

POTD July 25, 2013: Slickrock Trail near Moab, Grand County, Utah

Slickrock Trail near Moab, Grand County, Utah
Photographer: Jim Davis

Giant weathering pits or potholes like this one (about 16 feet across at the bottom) in the Jurassic-age Navajo Sandstone typically form along fractures and joints atop fins, knolls, and rounded domes. Potholes are created through a combination of physical, chemical, and biological processes that weather and erode the rock and are home to a remarkable array of ancient aquatic organisms.

POTD July 17, 2013: Crystal Geyser, Green River, Grand County, Utah

Crystal Geyser, Green River, Grand County, Utah.
Photographer: Taylor Boden

Colorful travertine (calcium carbonate) is deposited around cold-water, carbon-dioxide-driven Crystal Geyser.

POTD July 9, 2013: East of the Green River, Grand County, Utah.

East of the Green River, Grand County, Utah.

Photographer: Don DeBlieux

A summer evening arrives with the promise of cooler temperatures at the UGS paleontology camp near the Crystal Geyser Dinosaur Quarry.