Document Type

Honors Project On-Campus Access Only


Thirty-seven samples were collected from the volcanic ash bed at Ashfall Fossil Beds State Historical Park in Nebraska for geochemical analysis. Two hypotheses are tested: (1) the ash bed is from a single volcanic eruption, and (2) it is correlated to the 11.93 Ma Ibex Hollow tuff. Major and trace element content was determined using an Energy Dispersive X-ray Spectrometer (EDS) and an X-ray Fluorescence Spectrometer (XRF), respectively. Results show one distinct chemical cluster, suggesting a single volcanic source. When these samples are compared with previously published data, the Ashfall ash layer is tentatively correlated to a younger volcanic source, approximately 10.5 Ma. Additional analyses are needed to test the validity of this interpretation.



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