GSM 2015 March Nevada - Day 4
May 14, 2015Public
Photo: Wednesday morning, we gather at the base of Frenchman Mountain, just off Nevada highway 147 (Lake Mead Blvd.), just east of Las Vegas.
Photo: Frenchman Mountain is made up of rocks similar to those found on the bottom of the Grand Canyon; it formed when faulting elevated and tilted the rocks followed by erosion, giving it its sharp triangular profile.
Photo: Our local geologist leader, Nick Saines, explains what we are seeing.
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Photo: Nick Saines points out features in the rock.
Photo: Frenchman Mountain is a site of the Great Unconformity, seen here, with the tilted Paleozoic strata underlain by Paleoproterozoic Vishnu Schist, which is some of the oldest rock on the North American continent, having been created about two billion years ago.
Photo: Jenny touching the Great Unconformity. The Great Unconformity separates the Tonto Group from the underlying, faulted and tilted sedimentary rocks of the Grand Canyon Supergroup and vertically foliated metamorphic and igneous rocks of the Vishnu Basement Rocks. It here represents a gap in the rocks of 1.2 billion years.
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Photo: Frenchman Mountain lies on a north to north-northeast trending ridge about 2000 feet above the nearby valleys.
Photo: Frenchman Mountain exposes a sequence of Phanerozoic strata equivalent to those found in the Grand Canyon.
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Photo: The Tapeats Sandstone of the Tonto Group overlies the Vishnu Basement Rocks.
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Photo: View of Las Vegas looking west from Frenchman Mountain.
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Photo: View of the Las Vegas Strip. Unfortunately, there was a fair bit of haze that day.
Photo: In the background are the mountains containing Red Rock Canyon, which we visited on Day 1.
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Photo: We collect trilobite fossils at the base of Frenchman Mountain.
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Photo: Each person has a different posture for collecting fossils.