Paleontology and geology
Dramatic climatic fluctuations caused sea level to rise and fall several times during the Quaternary. Scarps (cliffs) along the major rivers of Virginia indicate the positions of the former shorelines produced by these changes in sea level. Flooding of the Susquehanna River Valley, caused by rising sea level, formed the Chesapeake Bay approximately 7,000 years ago. Analyses of tree rings and pollen present in lake sediments help paleontologists to reconstruct Quaternary climates.