Abstract

In a multidisciplinary effort, uppermost Cretaceous and lower Tertiary Laramide synorogenic strata in the Denver Basin have been dated using biostratigraphy, magnetostratigraphy, and radioactive isotopes. The resulting calibrated framework permits biotic and stratigraphic events to be examined in a spatial and temporal context. Synorogenic sediments accumulated in two distinct pulses separated by about eight million years. Faunal changes are evident across time and, to a lesser extent, space. In addition to evolutionary changes through time, floras show distinctive distributional patterns that reflect the ancient landscape and indicate the presence of Paleocene monsoons on eastern flanks of the Rocky Mountains. Observations by the Denver Basin Project team have been used to create a series of rigorously documented paintings reconstructing ancient Denver Basin landscapes. As a result of our stratigraphic work, bedrock aquifer patterns in the Denver Basin are better quantified. The Arapahoe aquifer is comprised of a series of buried alluvial fans and does not form a uniform layer across the Denver Basin.

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