These rocks were created by the particles settling to the bottom of the sea and cementing and bonding together. Sedimentary rocks left from the Triassic, Jurassic and Cretaceous periods of the Mesozoic era and from the beginning of the Tertiary period. Most rocks were laid down by water as sand gravel and mud. This has been converted into solid rock by the weight of the layers above them and by cementing lime, silica, and iron. Fossil sea shells, fish, trees, snails, bones and tracks of land animals, and sometimes dinosaurs can be found in these rocks.
Lower layers are mostly mudstones, seltstones, sandstone.
Navajo Sandstone, thickest layer of rock, was formed by wind deposited sand grains. This is the background for the beginnings of the development of the awesome rock formations found in Utah.