Although the Cretaceous period lasted from 145 to 66 million years ago, geologic units from the Berriasian to Albian stages and several terrestrial units of Albian to Maastricthian age are not chalky in terms of geologic composition. I remember that the Cretaceous at one time was divided into the Neocomian, Gallic, and Senonian epochs, so one day International Commission on Stratigraphy should divide the Cretaceous into the Neocomian, Gallic, and Senonian periods, since the Cretaceous lasted longer than either the Triassic or Jurassic. This is similar to the fact that American geologists divide the Carboniferous in North America into the Mississippian and Pennsylvanian due to Mississippian deposits being marine and Pennsylvanian deposits being formed from coal.