Four Sediment Cores Were Removed from the Floor of an Inland

Multiple Choice

Four sediment cores were removed from the floor of an inland sea. The sea was in existence intermittently throughout the entire time that terrestrial life has existed. Researchers wish to locate and study the terrestrial organisms fossilized in these cores. In the diagram, the cores are illustrated as vertical columns, with the top of the column representing the most recent strata and the bottom representing the time when land was first colonized by life. Which of the following factors would best allow a researcher to assign absolute dates to the fossils in the sediments?

A) knowledge of the order in which the fossils were deposited
B) knowledge that the sediments had not been affected by underwater currents during their deposition
C) presence of volcanic ash layers between the sedimentary strata
D) equal spacing of fossils throughout the columns