During the late Jurassic, in North America, in the wet seasons the rains were plentiful and floods spread across the plains. (Dinosaur Manufactuers)Flood sediment was deposited over the landscape causing prolific plant growth on which animals browsed.The original flood deposits were disturbed by the trampling feet of the animals – called bioturbation The alkaline lakes formed beds of limestones. Ribbons of river sediments run through the whole sequence.(animatronic dinosaur) Dinosaur fossils are found as isolated bones on the flood deposits or sometimes as associated skeletons in the river sediments.
The Morrison Formation is seen most obviously as a ridge along the foothills of the modern Rocky Mountains.(walking dinosaur costume)In the dry season rivers dried to a trickle, and ponds became hard-packed mud. Water evaporation brought up the mineral calcite and left it as lumpy beds of limestone beneath the soil surface. Animals migrated into areas where there was still food to be had.
The Morrison Formation, named after the Colorado town of Morrison. USA, consists of 30-275m (100-900ft) of shale, siltstone and sandstone, and stretches from Montana to New Mexico. Its landscape was once that of a riparian forest, or forest growing on riverbanks. The most famous outcrops of the Morrison Formation are in Dinosaur National Monument in Utah, and the Fruita Palaeontological Area and Dry Mesa Quarry, both in Colorado. At Tendaguru in Tanzania, a similar environment existed at exactly that time and almost the same range of animals lived there.
Rivers full, and depositing current- bedded sediments. Water surface higher than surrounding plain.
River banks built up from flood deposits, forming high levees.
Temporary ponds where springs leak through levees.
Alkaline lakes poisoned by lime from bedrock.
Most vegetation on river bank.
Diplodocus and Stegosaurus drinking from freshwater pond.
Brachiosaurus feeding from riverside trees.
Dead creature washed downstream by flood
Indistinct bioturbated beds of flood sediment.
Dinosaur remains as individual bones scattered across flood plain beds.