How do we get all these tiny shells from deep within the sediment, either underground or under the sea floor? We use sediment cores, which are tubes of sediment extracted from the ground. Sediment cores are widely used by geologists in many areas of research to sample sediment and rock from underground. This sediment is layered under thousands to millions of years of younger sediment, and understanding the order of the sediment layers, and the species of shells contained within these layers, can be very informative and can address a variety of types of scientific questions.

Once the cores are brought to the surface, samples can be taken from them. For example, this is an image of what the core looks like, laid out side by side, before the sediment is removed. The shell hash to the right of it is what remains after sieving and rinsing out the muddy sediments.

The cores cut through many different environments that represent the history of the area. Some sections are terrestrial deposits (on land). They are generally devoid of mollusks, with the exception of land snails. They also contain rocky sediments and plant material. However, most of the samples come from marine environments. There are a few species that are found primarily in shallow marine environments, such as Lentidium mediteraneum, a bivalve that is the most common species found throughout our cores. Other shallow water genera include Donax and Abra. Samples from deeper marine waters, contain such genera as Pitar, Euspira, and Nucula. Since these species still exist today, we know their preferred environment and likely depth range. This allows us to track environment and water depth in the past using our Po Plain cores.