Mapping the Continental Shelf of the MBNMS

Abstract

The US Geological Survey is investigating the seafloor geology and active geologic processes within the Monterey Bay National Marine Sanctuary (MBNMS). One of the principal goals of the MBNMS project is to acoustically image the continental shelf at better than 1-m pixel resolution. To this end we have collected side-scan-sonar data and constructed mosaics of the data at 40-cm pixel-resolution. A total of over 1000 square kilometers of the continental shelf in the Monterey Bay area have been mapped to date.

In the acoustic backscatter imagery presented in this poster of the northern Monterey shelf, high backscatter is caused by rock outcrops, coarse-sand deposits, and the pipeline seen west of downtown Santa Cruz. The inner shelf of northern Monterey Bay, out to about 40-m water depth, contains a modern wave-cut platform of outcropping bedrock. Rythmic patterns of high-reflectivity south of Santa Cruz represent coarse sand deposits, presumably in transit along the inner shelf/coastal zone. Such sands periodically fill the Santa Cruz small boat harbor channel and must be removed by dredging on a regular basis.

The seafloor maps and other results from this project will be available on our web sites as well as distributed via CD-ROM in 1999.

This abstract (WPG# M98-0261) is from Monterey Bay National Marine Sanctuary Symposium, Sanctuary Currents '98, Human Influences on the Coastal Ocean, Poster Session, 1998.