The Sea’s First Tides – in Utah

Submitted by Deborah Cramer

The Sea’s First Tides – in Utah

A climber scales a piece of ancient seafloor in Utah’s Wasatch Mountains
© Andrew Burr

Utah’s Wasatch Mountains, more than five hundred miles from the ocean and five thousand feet above sea level, are remnants of ancient seafloor that record the ebb and flow of the planet’s early tides.

Some 750 million years ago, the ancient continent of Rodinia was breaking up while the Pacific Ocean basin was forming. Nevada was located along the coast. The sea and its tides reached inland, just outside what is now Salt Lake City.

Today, the steep cliffs of Big Cottonwood Canyon hold the record of those ancient tides. Within huge slabs of shale that once belonged to the ocean, alternating layers of sand and silt mark the turning tides (silt was dropped at slack tide, sand when water flowed more forcefully).

The passage of the moon around the earth and the earth around the sun dictate the rhythms of tides. Those rhythms recorded in Big Cottonwood Canyon suggest that when the ocean lapped on the shore of now land-locked Utah, the days were 25% shorter – 18 hours instead of 24!

References and more information

Geology of Big Cottonwood Canyon

Hintze, L.F. and Kowallis, B.J., 2009. Geologic History of Utah. Brigham Young University Geology Studies Special Publication 9, 225 pp.

Eldredge, Sandra N., et al. Geologic Guide to the Central Wasatch Front Canyons. Public Information Series 87, Utah Geological Survey.

Bugden, Miriam. Geologic Journey Through the Central Wasatch Range. Utah Geological and Mineral Survey
Utah Geological Survey

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