Undergraduate Honors Theses

Thesis Defended

Fall 2016

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Geological Sciences

First Advisor

Stephen J. Mojzsis

Second Advisor

James Hagadorn

Third Advisor

Charles Stern

Fourth Advisor

Noah Fierer

Abstract

Stromatolites are laminated structures that occur from the collection and binding of small grains of sediment by microorganisms. The appearance of stromatolites indicates a period of decreased grazing at a specific point in earth’s history. Stromatolites in the Lykins Formation of the Eastern slope of Colorado and Southern Wyoming flourished during the Permian-Triassic mass extinction event, which occurred approximately 250 million years ago (mya). This mass extinction event caused more than 90% of marine and terrestrial species to perish.

Due to their nature, the remains of the individual microbes that produced stromatolites are not preserved in the geologic record, but the structures from the laminated sediment are. It is from these stromatolite remains that a deeper analysis was conducted on the morphology and stromatolite dome spacing of the stromatolites in the Lykins Formation. Using specialized measuring techniques adapted for each morphology type, it was found that the larger the stromatolite dome spacing and dome size, the less grazing occurred at the time of the stromatolite’s accretion. These results demonstrate the effect of the predator-to-prey relationship in stromatolite populations when their population is not controlled by grazing, as evidenced by the increase in dome size and dome spacing.

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