To log you will need to post a photo of yourself or your group with the earth formation in the background
and in an email to the cache owner, identify the oldest fossil bearing formation present,
along with the type of fossils and type of rock they are found in.
Strata are the hard evidence of the passage of time and changing climatic conditions in a given area. The rock types can give clues as to an area being covered in shallow water, deep water or glaciers. They can also give evidence to erosion or deposition of sediments.
The geological display at Schramm exposes layers of sedimentary rock ranging from Eudora Shale and Stoner limestone from the Paleozoic Era, 542 million years ago to Dakota sandstone deposited during the Cretaceous period 146-65 million years, to the windblown Peoria Loess soil of a more recent 1.8 million years ago.
The Paleozoic era strata are characterized by repeated cycles of deposition of marine limestone and shale and in places non marine sandstone and shale. Nebraska at this time period was a shallow sea that varied in depth over the span of years. Limestone strata was produced by remains of living organisms found in shallow, warm waters while the shale strata are composed of particles of preexisting rocks that have been deposited in deeper water that didn’t support the calcium rich organisms that produced limestone.
Towards the end of the Cretaceous period this shallow inland sea retreated. Sediments originating from the erosion of the Rockies, and carried by watersheds across Nebraska to deposit alluvium or particles of various sizes carried by running water and dropped when the flow rates can no longer sustain movement of the particles.
Glacial erosion during the Pleistocene epoch created sands and finer particle silts, that were carried by the winds to deposit what became the sand dunes and Loess. Over some areas this Loess was deposited to amazing depths.
To log this Earthcache you may post a photo of yourself or your group with the earth formation in the background (photo is optional) and in an email to the cache owner, identify the oldest fossil bearing formation present, along with the type of fossils and type of rock they are found in.
You will not need to wait for a response to log the cache online, however logs not meeting all of the requirements within a reasonable time frame will be deleted.
Schramm State Park Field Trip: Sedimentary Rocks, Stratigraphy, and Geologic History.
Dr. Lindsley-Griffin and Dr. R.J. Goble
With contributions from: Ms. Amy Carter, Dr. P.C. Grew, and Dr. M. A. Holmes
Department of Geosciences, University of Nebraska-Lincoln