Abyssal bedforms as indicators of changing bottom current flow: Examples from the U.S. East Coast continental rise

Abstract

Direct indications of circulation patterns in the deep sea (especially along continental rises and sediment drifts) can be obtained through the analysis of abyssal bedforms such as furrows and mud waves. Such direct evidence of current flow will supplement indirect indicators of circulation provide by paleochemical indicators preserved in ocean sediments. Water that sinks in the northern North Atlantic forms part of the Western Boundary Undercurrent along the continental rise of eastern North America and the understanding of temporal changes in the speed and depth of flow along this continental rise can provide important information on how the speed at which the global conveyor system is operating changes with time. Studies of furrows and mud waves along the Blake‐Bahama Outer Ridges show that they are active sedimentary features today, and that bottom flow speeds near the time of the Younger Dryas were increased over later intervals. A more detailed analysis of bedform structure and sediments is needed to more clearly show the timing and reason for this change in sedimentation pattern.