What is the Upper Cretaceous?
Q: What is the Upper Cretaceous?
A: The Upper Cretaceous is the last geological epoch in the Cretaceous period, which began 100.5 million years ago and ended 66 million years ago. It is traditionally divided into Lower Cretaceous (early) and Upper Cretaceous (late), because of different rocks that reflect the conditions in which they were formed.
Q: How is it subdivided?
A: The Upper Cretaceous is subdivided from lowest to highest into the Cenomanian, Turonian, Coniacian, Santonian, Campanian, and Maastrichtian ages.
Q: What type of rock can be found in chalk?
A: Chalk found in the Upper Cretaceous period is composed of countless millions of calcareous (CaCO3) plates called coccoliths, which are so small they can only just be seen with a light microscope; details require an electron microscope. The only other rock found in chalk is flint, which is siliceous (silica SiO2).
Q: What animals lived during this time?
A: During this time dinosaurs were dominant land animals such as Triceratops, Tyrannosaurus and Velociraptor while Mosasaurus was the dominant marine predator. Birds also became more diverse during this period.
Q: What plants developed during this time?
A: Flowering plants developed more and became dominant on land during this period.
Q: How did the Upper Cretaceous end?
A: The Upper Cretaceus ended with a K/T extinction event.
