Lykins Stromatolites Settle In On The Geology Time Trail (265 my)
The Crossroads Through Time Geology Time Trail has several new boulders pinpointing various geologic time periods in south central Colorado. The most recent arrivals are two Lykins Formation stromatolites placed at the 265 million year mark. The Lykins Formation is a layer of sedimentary rock that was oncea wavy layer of muddy limestone which outcrops and is visible today in eastern Fremont County.
Lykins stromatolites are placed at the 265 my mark
Stromatolites were the first fossils ever, and they still exist today in Australia and the Bahamas. They are mounds formed in shallow marine waters by matted layers of dirt and cyanobacteria (commonly called blue-green algae, but not really an algae at all). The bacteria extract carbon dioxide from the water and, through photosynthesis, produce oxygen. The earliest stromatolites, dating back 3.7 billion years, are now fossils found in Australia.
Earth’s early atmosphere was toxic, filled with poisonous gases and little oxygen. Over millions of years, stromatolites increased the oxygen in earth’s atmosphere until it could support life as we know it. This resulted in an entirely new environment, then the emergence of newly evolved life, and finally an explosion of diverse forms of creatures. Without the oxygen-generating stromatolite, life as we understand it, wouldn’t exist on earth.
The timing of the donation of the stromatolites was excellent. Dr. James Hagadorn of the Denver Museum of Nature & Science is currently doing research on the Lykins Formation and has recently assembled a Permo-Triassic team which is researching the boundary of the Permian time period (300-251 million years ago) and the Triassic time period (251-201 million years ago). The largest extinction event of all time took place at this boundary, when 95% of all marine species and 70% of all terrestrial vertebrate species died out, eventually leading to a new diversity of plants and the dominance of dinosaurs on land. This extinction event is known as the “Great Dying”. In December 2016, Karen Whiteley, a citizen-scientist member of that team, spoke in Cañon City about their research on the Lykins Formation in Colorado.
The Lykins Formation is made up of several layers called members. Each member was laid down in a slightly different circumstance. Karen believes the stromatolites found near Cañon City are from the Forelle Member of the Lykins (a bed lying below the Poudre Member and above the Falcon Member) and are most likely Middle Permian in age (272-260 my). This geologic time period is referred to as the Guadalupian Epoch, The Lykins Formation itself spans the Permo-Triassic boundary at 251 myo. The Lykins overlies the Fountain Formation (which usually has a more orange hue) in Fremont County. Further north along the Front Range running from Ft. Carson north to the Wyoming border, the Lykins overlies the Lyons Formation (aeolian or wind-deposited sandstone), but northeast of Cañon City the Lyons appears to gradually diminish and end, resulting in its direct contact with the Fountain Formation.
The Lykins was deposited during a dynamic environment with alternating wet and dry periods, varying from a shallow marine sea less than thirty feet in depth to being a desert with dunes blown in from the east coast. Today these “red beds” extend northwest from Fremont County to Wyoming, Idaho and Utah. The Fremont County Forelle Member outcrop is believed to be the southernmost in Colorado.
Fossils in the Lykins are fairly rare, but in addition to stromatolites, the Forelle does include fish scales, bivalves, gastropods (snails), and algae.
The DMNS team hopes to determine if the Permian-Triassic extinction event is represented in the Lykins Formation. Their paper “The Permian-Triassic transition in Colorado” can be accessed by scrolling down to Highlights on this website: http://dmns.org/science/museum-scientists/james-whagadorn/