Navesink Formation (Basal)

The Upper Cretaceous Navesink Formation is located in New Jersey and is between 66 and 70 million years old.  When the term "basal" is used in reference to a geologic formation, it means it is toward the bottom or base.  Since the material at the bottom was deposited first, we know that coprolites and other fossils in the basal portion are approximately 70 million years old.  During this time period, it was the floor of an inner sea shelf.  As sea levels rose and fell, sediments from shallower waters buried remnants of the creatures that lived in those waters.