The Primeval Rocks of Unicorn Point

October 28, 2022

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Photographer: Ray Boren

Summary Author: Ray Boren 

Above the southern tip of Antelope Island — a state park, and the largest isle in Utah’s Great Salt Lake — rise numerous outcrops so primordial that geologists say their stones are older than the basement rock found at the bottom of the Grand Canyon and are therefore among the oldest exposed on Earth. 

The first photograph here, taken on Sept. 22, 2022 — the Autumn Equinox — presents a curious set of banded, contorted and weathered metamorphic features on the island’s southernmost Unicorn Point. The second photo spotlights the outcrop’s eye-catching features: A a sculpted stone that looks like a fist punching skyward (or is it an abstract gargoyle of E.T. the Extra-Terrestrial’s head and long neck?). Another eye-catching feature from this outcrop is shown below; a folded, intrusive “Z” that fictional Old California hero Zorro might admire. Other formations, sometimes rounded, sometimes dangerously gritty and sharp, resemble knobby pillars or upright spears, or bear intriguing striped designs and raised quartz ribbons.

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Two-thirds of Antelope Island is composed of Farmington Canyon Complex stone — originally sedimentary rock that formed 2.5 billion or more years ago, which was subsequently altered approximately 1.7 billion years ago by metamorphic processes and intrusions, according to the Utah Geological Survey. These rocks and others on the island, once buried deep within the Earth, were heated at extreme temperatures, deformed, uplifted and exposed, and thus feature diverse examples of granites, gneisses, schists, quartzites, migmatites, amphiboles and pegmatites.

 

Antelope Island, Utah Coordinates: 40.9581, -112.2146

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