The Modern Setting Continuous tide gauge records around the Chesapeake Bay show that the rate of sea-level rise during the 20th century has not been constant and that modern rates are more rapid than those determined by geologic studies conducted two decades ago. Areas described as marsh in colonial times have given way to shallow creeks. Dead trees farther up tributary creeks characterize areas only recently submerged to become marsh. Tree stumps of former forests can be found beneath the sediments of tributary creeks. Sea-level rise continues.
Scientists disagree on the cause of the recent increase in the rate of rise.
Sediment compaction resulting from extraction of ground water is another popular explanation used today to account for land subsidence. The Chesapeake Bay has also been identified as one of four anomalous areas along the U.S. East Coast that appear tectonically active. A zone of crustal downwarping and sediment accumulation known as the Salisbury embayment has long been recognized beneath the Delmarva Peninsula. It is clearly possible for vertical movement to occur along such zones. Another geologic factor that might account for anomalous rates of sea-level change, at least for the mouth of the bay, is possible subsidence related to compaction of the fill of a large buried impact crater that underlies much of the Norfolk, Hampton Roads, and Cape Charles area.