The Big Horn Mountains 60 miles to the west supplied the sediment of this exposed section of Tullock Formation (Fm). Tullock Fm. consists of alluvial fan and swamp deposits all the way back to the mountains. Sediments washing off the newly risen peaks were filling up the coterminously formed sedimentary basin (Powder River Basin). The huge coal mines we have here are mining the coal formed in those swamps at the base of the Proto-BigHorn Mountains. Those mountains were much higher when they were young plus the basin was deeper.
Huge blocks of the earths crust uplifted and correspondingly downwarped during a major tectonic compression episode called the Laramide Orogeny. Cloud peak is 13,175 feet and is visible in this image. The same compressional forces that uplifted the peaks, also downwarped the adjacent basin to the east. This Basin called the Powder River Basin. This basin the major source of coal in the US. The burning of this coal generates 30 percent of the electricity generated in the United States.
My ranch coincidentally sits directly on the western most edge of the Wyoming Black Hills. It is actually JUST east of the edge of the Powder River Basin. If I drive 2 miles west, I start to see alluvial fan sediment. These sediment fans stretch all the way from the Big Horns. Dissected into ridges by huge rivers washing off the peaks during glaciation. . These alluvial deposits are far reaching, called the “Tullock/Fort Union” formation. Major Mountain sized Anticlines and Synclines resulted from the continental wide compression.. Huge were the forces bending even the underlying crystalline Pre-Cambrian rocks. The rocks to clay washing off of those peaks filled the basin and washed just about to my front door.
Understanding the geology here takes many books to read, its a long list and growing 🤔😀📷
Location: near the Bliss DInosaur Ranch, WYoming/Montana borderlands
There is a reason we are called the “Bliss Dinosaur Ranch. T-rex’s Middle Toe Bone, Just before the HIGHLY desirable killing claw is a rare bone being on 2 per T-rex. The T-rex’s only constitute 2 percent of the fossil volume found in the Hell Creek Formation. This is about 1/400th of the volume of a t-rex’s skeletons proportionality so 1/400th of 2 percent.
Here the bone is still moist and has sand all over it from it’s excavation from a burial of 66 million years or more. . It was quite perfect (still is), needed NO superglue to hold it together or repair it in any way. (way unusual) It is also rare for a river water deposited bone to be “perfect” after being washed unknown miles down an ancient river, buried, washed away in a scour or channel change, rinse and repeat for 3 million years of this sand being dumped by huge rivers from the highlands to the west of here transported by water and left here for me to dig in.. I earned a Masters Degree along the way in a related geologic field to Paleontology and have been a geologist/paelontologist since I was 5 years old. It was no coincidence I moved to this spot 20 years ago. The geologic maps said this ranch was covered in younger rocks than the dinosaurs. I knew they were wrong when I asked the guy who dug all the wells in the area how far down it was to Fox Hill formation which is the local aquifer (he had worked in the area of our ranch) where everyone around here gets their water. Hell Creek is 700 feet thick. Fox Hill is the Beach Sand that the DInosaurs walked on and is stratigraphically lower/under the terrestrial Hell Creek DInosaur Bearing sand. 700 feet of Hell Creek minus 500 feet to Fox Hill made me suspect there was at least 200 feet of Hell Creek fossiliferous (possibly) layers on the surface. I was right and it was a few years before I figured out where 25 micro-sites and a bone quarry were . I also located a partial triceratops on a neighboring ranch. There are a few other spots I know of…🤔
There are in excess of 10K fossils in the ranch collection currently. Before you ask, I do not nor ever will sell fossils. They will go as a collection to a museum some day.
FYI, it is illegal to collect vertebrate remains on public/BLM/State/Indian land. Leave them be. You can only legally collect such fossils from private deeded land. So before you look, ask the landowner for permission…preferably written and no I don’t have people randomly come up here to look around on their own. No horn collectors, no hunters please. This is a private ranch.
The Bliss Dinosaur Ranch, Wyoming/Montana borderlands.