Publication Date


Document Type


Committee Members

David Schmidt (Committee Member), William Slattery (Committee Chair), John Stireman (Committee Member)

Degree Name

Master of Science (MS)


A stromatolite is a laminated benthic microbial deposit. Its uniqueness arises from being present since the Precambrian to the present. Stromatolites recorded a peak time during the Mesoproterozoic, subsequently they witnessed abrupt rises and falls in abundance with the steepest decline in the Ordovician period, from which it never recovered from. There is no consensus yet regarding the reasons behind the decline of stromatolites. Thus the decline of these microbial deposits remains an enigma. Additionally, a literature gap exists regarding the reasons that specifically led to the Ordovician decline. Accordingly, the focus of this literature-based MSc. thesis is to find the reasons that led to the stromatolites decline in the Ordovician - using abiotic and biotic palaeoecological tools - an approach that has not been implemented before in the study of stromatolites. The conclusions are that abiotic factors such as calcium carbonate ocean saturation were likely responsible for much of the decline. However, present-day distributions in harsh environments and negative relationships between stromatolites and metazoan radiations indicate a role for biotic factors.

Page Count


Department or Program

Department of Earth and Environmental Sciences

Year Degree Awarded