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Fountain Formation of Red Rocks Samuel Cooke The Fountain Formation was formed 300 million years ago, during the Pennsylvanian Period of the Paleozoic Era. However, the Idaho Springs Formation, formed during the Precambrian Era, is 1700 million years old.(Taylor 8) This means that there is a minimum of 270 million years (which would be about 6000 feet worth of rock) of rock that is missing. The only explanation for where the missing rock went is that when the ocean that used to cover all of Colorado existed, the missing rock was uplifted above the surface of the ocean due to plate tectonics and created mountainous islands above the surface. (Taylor 8-9) These islands formed the Ancestral Rocky Mountains (no relationship between them and the current Rocky Mountains). The mountains were subjected to the erosion of the atmosphere, and hydrosphere and were ultimately eroded away as geologic time passed. (Taylor 9) So while the Ancestral Rocky Mountains weathered and eroded, so did the Idaho Springs formation. When the Idaho Springs formation weathered, it was eroded by the steep mountain streams with high flow velocities of the Ancestral Rocky Mountains. This means that all of the rock in the Fountain Formation could, and probably did, come from the Idaho Springs Formation because all of the rock in the Fountain Formation can be found in the Idaho Springs formation. (Taylor 10) In addition, we believe that the erosional source was the Ancestrial Rockies because the boulders, cobbles, pebbles, and coarse sandstone of the Fountain Formation suggests that the Fountain Formation was formed close to its erosional source and that the source came from high mountains, I.E. the Ancestral Rockies. (Taylor 11) Geologic Timeline Pt 1 The Fountain Formation was formed in Pennsylvanian Period of the Paleozoic Era. It was formed from the Idaho Springs Formation and its erosional source was the Ancestral Rockies. During this time, all of Colorado was covered by an ocean, so it was primarily eroded by the hydrosphere during this time. While this was happening, the continents were all coming together to form Pangaea. At this time, the ocean started to recede due to the uplift of the continents, and the Fountain Formation was now above the surface. Here it was subjected to more erosion, this time by the atmosphere. (UCMP. Berkley) Geologic Timeline Pt 2 So as the Paleozoic era came to a close, and the Mesozoic began, everything was still the same as the new era began to the Fountain Formation. A more tropical climate, with high humidity, heat, and jungles were in Colorado. That was about to change, however. In the Mid-Triassic period Pangaea began to break up to form two new continents, Gondwana (South America, Africa, India, Antarctica, and Australia), and Laurasia (North America, and Eurasia). This meant that the Fountain Formation was getting farther away from the Equator, which meant it was going to get colder. During the course of the Mesozoic era, the continents continued to drift apart, and North America got farther and farther away from the Equator. (UCMP.Berkley) Geologic Timeline Pt 3 As North America continued to drift away from the Equator, it got colder and colder in the Fountain Formation. This means that glacial weathering and erosion started to take place, which continues to this day. After the mass extinction of the dinosaurs, the Cenozoic Era began. During this era, the continents drifted to where they are today. (UCMP.Berkley) Composition of Red Rocks Sandstone Mudstone Gneiss Quartz Feldspar Iron(the iron in the rocks was oxidized and that’s what gave red rocks its red color) Works Cited Taylor, Andrew M. "FOUNTAIN FORMATION. PENNSYLVANIAN PERIOD." Guide Book to the Geology of Red Rocks Park andVicinity. 4th ed. Golden, CO: Cataract Lode Mining, 1992. 8-12. Print. UCMP. "Web Geological Time Machine." Web Geological Time Machine. UCMP. Web. <http://www.ucmp.berkeley.edu/help/timeform.html>.