The Red Rocks Park contains many layers of a cross bedded red fusion of coarse to fine grained sedimentary rock called the conglomerate Fountain Formation. The red rock is comprised of the ancient sedimentary remains of the long gone ancestral Rocky Mountains. Like a red ‘rock classic’ composed of larger notable fragments layered with finer grained rifts. The rock mixed with materials like clay and silt sediments. They form a very solid synthesis that has lasted eons from as far back as the Late Pennsylvanian period. Three Hundred Million years ago, give or take a few million years, these sediments began the foundations for the Red Rocks that form the park.
Appropriately named in Geologic Timeline of our PALEOZOIC Era is, “The Fountain Formation.” The eastern edge of the Rocky Mountain sediments deposited in this Carboniferous Period is the bulk material that formed what we know today as the monolithic Red Rocks Park, Roxborough State Park, Garden of the Gods and Boulders’ Flatiron locations.
Our Ancestral Rocky Mountains contained metamorphic rock of Granite, Gneiss and Schist’s made of a majority of the minerals feldspar and quartz which comprise these iron rich sandstone sediments seen in the Red Rocks Park. As time went by these Pennsylvanian Period deposits were fueled by torrential rivers in what geologists call a fluvial and alluvial river system. Combined minerals with clay and silts plus elements like iron deposited many layers upon cross bedded layers which became conglomerates under the pressure and heat over the many millions of years. One of The best preserved examples of the Fountain Formation we see today is the Red Rocks Park and Amphitheatre. At this point in Natural History a great nonconformity happens with the 1.8 billion year old metamorphic rock, of what is now Mt. Morrison, and the 300 million year old “Red Rock Fountain Formation.” One can span the great Nonconformity of 1.5 billion years with your hand. The mystery here is that sediments didn’t get laid down for over 1.5 billion where in other places including areas in this state they did get laid down.
The Red Rocks Park went through a couple of the few big geologic time periods. The Carboniferous period saw the formation of the rock. The Permian Period sees the reworking of the ancient sedimentary red rock into dry iron-less natural buff colored sand dunes seen in the next small Red Rocks Park sandstone called the “Lions Formation.” The Red Rocks then was similar to that of the environment down in the Great Sand Dunes National Park here in present day Colorado.
During the Lopingain Epoch of the Permian period geologists count some 50 million years forward from the Late Pennsylvanian Period still in the PALEOZOIC era here. We are at the end of Permian Period, circa 252 Mya, and the planet experiences one of the biggest mass extinctions of our planets’ history here in the Forelle stratigraphy. Some say by 250 mya 70% of fauna and flora had disappeared at this time. With an estimate of 95% of all ocean life on the planet also disappearing. Some of the best preserved fossilized Colorado Stromatolites have been found here in the Lykins Formation within Red Rocks Park. The Lykins Stromatolites seem to have existed on the other side of the Permian Extinction and may or may not have survived the mass die off of the majority of terrestrial life forms. This Lykins Fossil Formation is a bit under studied in the area of Sedimentology, Paleontology and Paleo Environments with an exception in Geology, needs further research to clarify. One endeavor this amateur field researcher is currently researching with the help of the Morrison Natural History Museum, Dr. Robert T. Bakker, Matthew T. Mossbrucker and Field Friends.
The next and last geologic time period of the Red Rocks Park is along the eastern park boundary and is mostly in the Triassic Period. The Triassic period saw the rise of life again from that Permian extension from around 252 Mya counting down another 50 million years to 202 Mya. Paleontologists believe that many of the Jurassic Dinosaurs and non-Dinosaurs evolved from this era from about 204 Mya.
Around the time of the Laramide Mountain Orogeny an uplift of the current Rockies occurred some 72 to 45 million years ago, all the sedimentary red rocks here were pushed up at a near 40 degree angle seen at this angled tilt today.
Sculpted by times’ patient chisel this ongoing carving is forever shaped by wind and waters power struck hammer blows checked by weathers erosive freeze and thaw. The Fountain Formation, Morrison Formation and the Dakota Sandstone Formation rest more than two miles and 10,000 feet underneath the layers of Denver and yet sticks up here in the Foothills of Morrison.