The Morrison Formation
rocks slowly following the course the river carved in the rock
_ In the western region of the United States lies the Morrison Formation. It ranges from Montana to New Mexico and dates from about 156.3 to 146.8 million years ago. The formation created a basin whose deposition was so great that the shallow sea covering most of the region was pushed into Canada. The Morrison Formation is composed of mud stone, sandstone, siltstone, and limestone. These sediments make up the Windy Hill member, Tidal member, Salt Wash member, and the Brushy Basin member. The clay of the formation is ash derived, which swells when wet and shrinks when dry. The area with a highly vegetated flood plane with quick flowing meandering rivers that drowned dinosaurs as they tried to reach their food source. As the continent drifted Northward climate change caused the rock to oxidize, killing all vegetation. These factors combined, explained the presence of the many dinosaur fossils and uranium ore.
_ The Mars Society Utah base, in front of the Morrison Formation.