|  | Stratigraphic Correlations Subsidence and fault displacement around producing fields also can be measured directly by using basic coring techniques. Correlation of shallow stratigraphic markers in sediment cores provides a basis for determining the magnitude of displacement relative to some datum such as mean higher high water. Figure 6 shows that the correlated beds have been displaced progressively downward 35-63 centimeters (cm) comparedto the adjacent marsh surface. Preservationof the marsh sediments beneath ameter of water is clear evidence that themarsh surface subsided first to form theopen water area. Subsequent erosion ofthe marsh sediments was minor comparedto subsidence.« Releveling Surveys | Subsidence Rates » |
