Real Science Radio hosts Bob Enyart and Fred Williams discuss polystrate trees, polystrate jellyfish, polystrate tadpoles, and many other kinds of polystrate fossils including vertically buried leaves, a mesosaur buried in varves, a whale in diatoms, a school of whales vertically through four strata, an organism's delicate spines radiating through solid rock strata, nautiloids standing on their points in solid limestone, a school of perch, a dinosaur footprint, and three-dimensional trilobites. To hear Part 1, and to see our list, just click on over to rsr.org/polystrates, and see especially the photos of the polystrate footprints and the polystrate leaves, at rsr.org/polystrate#footprints and rsr.org/polystrate#leaves (or, for the prints, just below). - Dinosaur Footprint Polystrates: Two photos, bottom right, and another below that (with two granddaughters of an RSR listener) were taken at the USA's #1 track site as ranked by a panel of paleontologists, Denver's Dinosaur Ridge. Dinosaur footprint polystrates Colorado's famous Dinosar Ridge footprints are pressed into the Dakota rock formation. The RSR hosts are radio guys and not geologists but Bob recalled that these deposits (we think they're the Plainview Formation of the Dakota group) stretch for hundreds of miles around the Denver hogbacks. So, how much scientific curiosity do mainstream geologists have regarding the polystrate footprints there, and what they require of the rapidity of the formation of their layers? A single polystrate establishes that these deformed layers, just west of Denver off of Interstate 70, were deposited rapidly enough that multiple strata were all still soft at the same time a dinosaur stepped into them. And what's more, those layers appear to be consistent in many ways with their underlying layers, suggesting a similar depositional history. Dinosaur Ridge Question: Does mainstream geology have a term for these kinds of polystrates? Answer: No. Question: Do mainstream geologists want to know whether their explanations for upright trees can explain other kinds of polystrates, including dinosaur footprints? Answer: No. Question: If polystrate footprint fossils indicate the rapid deposition of some iconic rock layers that cover a great extent in the Rocky Mountain region, would mainstream geologists be interested in knowing that, or even, in exploring it? Answer, sadly: No. Another question that is asked frequently is how long ago were these rocks of the Morrison and Dakota Formations laid down? The Field Guide gives 150 million years ago for the Morrison, in the upper part of the 208-144 million year ago Jurassic Period. A value of 100 million years ago is listed for the Dakota Formation, in the lower part of the 144-66 million year ago Cretaceous Period. Scott (1972) lists each forma- tion as about 300 feet (100 meters) thick. A crude estimate of average depositional rates can be made by dividing 200 meters of strata by 50 million years, yielding an average of 4 micrometers per year. Being off by a factor of about 2 in either or both of these numbers does not really affect the illustration... Nearly everyone can see that nothing can be buried and preserved at that slow rate. Dinosaurs, especially, need to be covered with at least their own thickness of sediment before they rot or are scavenged... Though not mentioned in his Field Guide, [Martin] Lockley has verbally claimed to have found some dinosaur footprints in the [Dinosaur Ridge] area that are so perfect that he can even see the texture of the skin of the feet. Preservation of such features necessitates burial by about a cm of sediment in a fraction of a day in gentle, non-erosive conditions. Otherwise wind, water currents, rain, or other animals would obliterate [such features]. Waisgerber (1990) reminds us that fresh deposits are particularly vulnerable to erosion prior to consolidation and cementation. Though it varies with habitat and moisture conditions, the rate of destruction of