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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.
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