Paleontology and geology
Louisiana was mostly coastal plain and shallow sea during the Quaternary, but glaciers further north affected the climate and caused fluctuations in sea level. Fossils of mastodons and spruce pollen indicate that cooler conditions than those of today prevailed in the Louisiana of the Late Quaternary. Some Quaternary gravels contain Paleozoic-age fossils of brachiopods and other marine organisms. These were eroded from older marine sediments deposited in the central part of the U.S. and carried by rivers and streams into Louisiana during the Tertiary and Quaternary.