Preliminary Report of Stratigraphy and Fossil Leaf Localities from Happy Canyon: I-25 CDOT Climbing Lane Project
DUNN, R.E., Denver Museum of Nature and Science, 2001 Colorado Boulevard, Denver, CO 80205-5798

In February 2000, fossil leaf locality prospecting and stratigraphic measuring of geologic sections began on a road-cut located on the west side of I-25, one mile south of Lincoln Avenue between mileposts 191.5-191.8. This project was initiated by CDOT (Colorado Department of Transportation) paleontologist Steve Wallace, who recognized good exposures of the Denver Basin paleosol and the presence of well-preserved fossil leaves at various locations along the exposed outcrop. All rock units of this study are from the Denver Formation, which was deposited in early Paleocene time. All leaf localities discovered in this study are from D1 strata (below the Denver Basin Paleosol). The main goals of this project were 1) the salvage paleontology of scientifically valuable fossil specimens, 2) stratigraphic measuring of the outcrop to assess the position and depositional setting of leaf-bearing units, and the Denver Basin paleosol, 3) to correlate this outcrop with existing knowledge about the geologic history of the Denver Basin, as part of the Denver Basin Project headed by the Denver Museum of Nature and Science.

In total, seven geologic sections were measured along the exposure allowing for the construction of a panel diagram to correlate paleosol exposures, various stream channels, and leaf localities along the entire outcrop. Two excellent fossil leaf localities were identified and quarried. One significant fossil locality (Sick of Sycamores, DMNH 2339) was quarried by census-counting, yielding a total of 1,041 leaf specimens of Platanites sp., 16 other unidentified angiosperm leaf-types, 2 different conifers, and four types of ferns. Additionally, palynological and paleomagnetic samples were taken and are currently under review.