Stop #4 (12:30 p.m.) - "Strike Valley". The Morrison formation is at the very top of the hill on the other side of the road. The Lykins (bottom of valley) has more shales and mudstones which are more easily eroded. So, this valley was naturally eroded away. The Department of Transportation to advantage of this natural valley for its road.
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![Lykins Formation: consists of red, thin-bedded, sand siltstones and shales, including dolostone and limestone layers. The image here shows layers of fossil algae known as Stromatolites. The limestone, dolostones, siltstones, and shales formed in a marine environment.\n\nThe stromatolites are present in the Forelle member (dolostone) of the Lykins. These algal mats are very calcareous and fizz intensively with a drop of hydrochloric acid (HCL). This is the side view of a very large stromatolite showing the thin laminations. [Stromatolites: Structures produced by cyanobacteria by entrapment of sediment grains on the sticky surfaces of the bacteria.]](img_8139_thm.jpg)
Lykins Formation: consists of red, thin-bedded, sand siltstones and shales, including dolostone and limestone layers. The image here shows layers of fossil algae known as Stromatolites. The limestone, dolostones, siltstones, and shales formed in a marine environment.
The stromatolites are present in the Forelle member (dolostone) of the Lykins. These algal mats are very calcareous and fizz intensively with a drop of hydrochloric acid (HCL). This is the side view of a very large stromatolite showing the thin laminations. [Stromatolites: Structures produced by cyanobacteria by entrapment of sediment grains on the sticky surfaces of the bacteria.]
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Lykins formation, Forelle member: Side view of stromatolite. Over time, calcareous sediments (limestone) and other materials were trapped in the layers of filamentous colonies of cyanobacteria. When living, the stromatolites live in shallow, warm water and are dome shaped. Living examples can be found in Shark Bay, Australia and the Gulf of California.
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Lykins formation, Forelle member: Side view of stromatolite showing the thin algal mat laminations. It's believed that the widespread presence of stromatolites contributed to the conversion of carbon dioxide to oxygen in the Earth's atmosphere.
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Top of stromatolite in Lykins formation, Forelle member.
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Stromatolites (algal mats) occur all through the Lykins formation, Forelle member. The high salinity of the water where stromatolites form likely kept out snails and other 'grazers' which would feed on the algae.
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A very interesting modern phenomenon! The line of bushes across the center of the picture is actually near the contact of the Lyons and Lykins formations. The bushes thrive here for a reason. They like to grow in the nutrient rich Lykins formation, but their roots descend into the Lyons sandstone to get more water. Studies following the contact point have actually been performed just by following these lines of bushes.
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