“Bite-Size Bits of Local, National, and Global History”
“Bite-Size Bits of Local, National, and Global History”
Near Golden in Jefferson County, Colorado — The American Mountains (Southwest)

Our Changing Landscape-From Sea Floor to Mountain Top

Our Changing Landscape-From Sea Floor to Mountain Top Marker image. Click for full size.
By Charles T. Harrell, July 3, 2011
1. Our Changing Landscape-From Sea Floor to Mountain Top Marker
Inscription. •Colorado’s geologic history dates back nearly two billion years. Several mountain ranges have been uplifted and eroded away before the rise of today’s Rocky Mountains. The landscape you see in front of you has undergone many dramatic changes. This story starts at a billion years ago.

•The sea covers Colorado: 80 million years ago. Today’s Rocky Mountains did not exist. Where you are standing and all before you was beneath a shallow sea that covered the middle of the North American continent. Today, marine fossils are found in the sediments deposited at that time (Pierre Formation). •Sea retreats as mountains begin to rise dinosaurs leave footprints near subtropical coal swamps: 68 million years ago. As the seas withdrew, sand, mud, and clay were deposited near the shore (Fox Hills Formation). Coal formed near rivers in swamps (Laramie Formation). The environment was warm with ample rainfall. These sedimentary rocks now lie beneath the City of Golden. You can see dinosaur tracks and large leaf fossils in the Laramie Formation along the Triceratops Trail in Golden (see other sign).

•The mountains form highest 60-68 million years ago. Volcanic eruptions occur 64 million years ago. Uplift of the Laramide Rocky Mountains began about 68 million years ago. Rock fragments from the newly raised mountains are found in the sediments exposed in the Golden area (Arapahoe and Denver Formations.) 64 million yeas ago, lava covered the area forming the rock now at the top of the Table Mountains. The source of the lava was Ralston Dike north of Golden (see other sign).

•The Rockies today: 63 million to the present. During that time period, the Laramide mountains were eroded and the rock debris was deposited on the plains about to the level where you are standing on Lookout Mountain. Later, rivers from the high mountains cut deep canyons such as Clear Creek canyon. Along the mountain front, the softer rocks were eroded leaving the hard rock as Dakota Hogback, the Table Mountains, and the rocks under your feet.
Location. 39° 44.025′ N, 105° 14.335′ W. Marker is near Golden, Colorado, in Jefferson County. Marker can be reached from Lariat Loop Road. Click for map. Marker located at overlook in the parking lot to the Buffalo Bill Memorial Museum. Marker is in this post office area: Golden CO 80401, United States of America.
Other nearby markers. At least 8 other markers are within walking distance of this marker. What You Can See From Here Today (here, next to this marker); Lariat Loop Byway: Denver Mountain Parks (within shouting distance of this marker); Lariat Loop Byway: Buffalo Bill Museum (within shouting distance of this marker); Charles E. Kirk (about 300 feet away, measured in a direct line); Buffalo Bill (about 500 feet away); Recreation: Past to Present (approx. 0.4 miles away); Water Carves Canyons (approx. 0.4 miles away); Play in the Wind (approx. 0.4 miles away). Click for a list of all markers in Golden.
Categories. Natural Features

Credits. This page originally submitted on , by Charles T. Harrell of Woodford, Virginia. This page has been viewed 520 times since then and 97 times this year. Photo   1. submitted on , by Charles T. Harrell of Woodford, Virginia. • Bill Pfingsten was the editor who published this page. This page was last revised on June 16, 2016.
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