Open-File 1997–0290
This study presents the surficial and shallow subbottom geology of the insular shelf around Culebra, Puerto Rico. In view of the need for sand and gravel for construction purposes in the area, we inferred the thickness of unlithified, surficial sediment deposits from high-resolution acoustic-reflection profiles and described seafloor sediment samples collected with a Shipek grab.
There are three sheets presented in PDF, JPEG, and TIFF formats:
Coastal and Marine Geology Program - https://marine.usgs.gov/
Woods Hole Field Center -https://woodshole.er.usgs.gov/