An exposure from the Pliocene-Pleistocene Epoch within the Tulare Formation of the Kettleman Hills geographic area of California. The zone is named for a small snail species that is abundant within the formation.

An exposure from the late Pliocene Epoch within the San Joaquin Formation of the Kettleman Hills geographic area of California. The zone is named for a species of clam that is common within the formation.

In paleontology, a group of fossil taxa (a population of organisms) in a particular layer of sediment.

Ink that resists decay such as fading or water damage over long intervals of time. It is typically used in combination with archival paper.

A photograph taken from high elevation overhead such as an airplane or balloon (images taken from satellites are technically different from aerial photos, but often serve similar purposes).

An invertebrate animal, belonging to the Phylum Arthropoda, and possessing an external skeleton (exoskeleton), body segments, and jointed appendages. Arthropods include crustaceans, arachnids, and insects, and there are over a million described arthropod species living today.