If the bio-and mechanical turbation is small, the horizon is stable and its depth is a measure of the sedimentation since 1963. Below on the left James Sheu lifts a core from the sediments in Fearman Lake, Louisiana. As shown in the graph on the right, based on data taken in 1990, eleven centimeters of sediment had been added above the 137 Cs horizon in White Lake, Louisiana. Harish Dhurvasula worked with Cary Hardaway, one of Jim's students on a joint project. Shown below are Jim, Harish, and Cary on a trip to collect sediment core samples in North Lake on Redfish Point off Vermilion Bay.
North Lake is a shollow, quiet, brackish lake that has deep, soft, little-disturbed sediments.
The students have correlated the concentrations of various elements and other chemical parameters, such as pH and Eh with depth and date of deposition. Much of our recent field work has taken place in the Gulf of Mexico. We joined with them to study the rate of sediment deposition in the lagoon. Harish Dhurvasula, using both 137 Cs and 210 Pb dating techiniques, wrote his masters t hesis on this problem. Shown below is an aerial view of the island which I took on a flight with Tommy Michot in a fish and Wildlife Service plane.