Mexican Hat Rock in Southeast Utah
July 29, 2019
Photographer: Patti Weeks
Summary Author: Patti Weeks
The Mexican Hat Rock pops conspicuously into view along U.S. Highway 163 in southeastern Utah. It’s located a few miles north of the small village of Mexican Hat (named after the sombrero-looking formation) and about 25 miles (40 km) north of the Utah/Arizona border.
The parallel rock layers in this region belong to the expansive Permian Cutler Formation, which covers parts of Utah, Arizona, Colorado and New Mexico. Mexican Hat’s 60-foot (18.3 m) diameter caprock is comprised of Cedar Mesa sandstone -- the base is red siltstone and shale of the Halgaito Formation. The ancient Cutler rock layers (the oldest being over 300 million years old) were laid down by the recurring rising and falling sea levels of an ancient marine environment. This flat terrain was then uplifted during the Laramide Orogeny (an intense mountain-building event occurring between 35 to 80 million years ago) and formed numerous minor anticlines on the crest of southeastern Utah’s Monument Upwarp.
The Mexican Hat Rock lies just to the west of the folded 8-mile (14 km) long Raplee Ridge (as partially seen in the second photo) which has characteristics of both an anticline and a monocline. This ridge is also referred to as the Raplee Ridge Rug by locals, because its alternating red and gray zigzag layers, cut by the deep gullies in the monocline, resemble patterns of some Navajo woven rugs.
At Mexican Hat, Utah the highway passes into the vast Navajo Indian Reservation and crosses the San Juan River, which originates in the San Juan Mountains of southwestern Colorado. The landscape-carving San Juan River formed an extraordinary 1,000-foot (305 m) deep canyon seen at Goosenecks State Park a few miles to the northwest of Mexican Hat. Visible from a roadside overlook, this is one of the best examples of entrenched meanders in the world, winding 5 miles (12 km), yet stretching only one mile (2.5 km) as the crow flies.
Photo Details: Top - SONY DSC-HX400V camera; 34.82 mm focal length; f/4.5; 1/800 second exposure; ISO 80. Bottom - Same except 24.08 mm focal length; f/4.5; 1/1000 sec. exposure; ISO 80.