Paleontology and geology
Although the glaciers that covered northern North America during the Quaternary did not reach Delaware, they greatly influenced the Quaternary geology of the state. Much of Delaware is covered by sands and gravels laid down by rivers carrying water and sediment from the melting glaciers. Subtle terraces found in the state’s coastal areas were formed by the rise and fall of sea level as the ice sheets to the north waxed and waned. Mastodons and other large mammals roamed the land during this epoch. A few mastodon teeth and tusks have been recovered in offshore areas by fisherman, indicating that these areas were dry land when sea level was low during glacial intervals. Fossil pollen shows a change in plant communities between warmer and colder periods and fossil leaves are known from a few localities.