Abstract: Geologic Effects of Ocean Dumping on New York Bight Inner Shelf
S. Jeffress Williams
A detailed study intended to inventory marine sand and gravel resources was conducted using 824 km of high-resolution seismic-reflection subbottom profiles and 61 vibratory sediment cores. Analyses of these data together with bathymetric maps from 1845 to 1973 and ancillary deep-boring logs have revealed that much of the natural bathymetry and geologic conditions on the inner New York Bight shelf have been modified significantly by ocean disposal of waste solids since about 1888. Innermost parts of the Hudson Shelf channel have aggraded by ^approx 15 m and broad hills mask the former natural-channel morphology. Composition of the waste solids varies considerably; much of the early material was natural soil and excavation debris from construction of buildings, subway tunne s, and navigation channels. More recent wastes consist primarily of fine-grained dredge spoil, treated sewage sludge, and industrial acids. The natural geologic stratigraphy shows considerable variation also, making the distinction between natural and anthropogenic sediment difficult. Upper Cretaceous clastic strata crop out at Shrewsbury Rocks and variable thicknesses of stratified Quaternary sand and gravel predominate over the shelf. Cores from the Hudson Channel depression contain fine-grained sediments which appear to be natural relict-estuarine deposits. Deposition rates of solid wastes have been far greater than for natural sediment; most of the waste solids have remained in the original dump sites and are modified only slightly by present shelf processes.
AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC