Triassic, consisting of sandstone, limestone, and clays, and containing
fossils of gigantic reptiles and first mammals (small marsupials).
Jurassic, or Oölitic, consisting of limestones, coral rags, clays, and
marls, and containing fossils of bird-reptiles and several species of
marsupials.
Cretaceous, consisting of clays, sands, soft limestone, and lignites,
and containing fossils of new bird-reptiles.