The accompanying map depicts the seafloor declivity and fall lines , displayed over a bathymetric base , on a portion of the continental slope in the Gulf of the Farallones, central California. The map was prepared as part of an extensive geophysical and sediment-sampling program whose purpose is to map and interpret the offshore geology of the Farallones region for application to resource and environmental concerns. The seafloor in the region is littered with debris that includes sunken ships and barrels of low-level radioactive waste.
Seafloor declivity is the slope of the seafloor measured from horizontal.
A fall line indicates the direction of steepest slope. One application of this map is to evaluate the gravitationally induced movement of objects on the seafloor. Objects in areas of steep declivity are more likely to move in response to gravity than those in areas of shallow declivity, and if they do move, they will follow the general path of the fall lines. Computer programs and techniques were developed within the USGS to store, extract, manipulate, and display these data. The maximum declivity in this area is 33.4 degrees.