USGS Home
Contact USGS
Search USGS

Figure 43. Using a hydraulic drill adapted for underwater operation, a scuba diver drills a core from a head of Montastrea annularis coral at Hen and Chickens patch reef off Plantation Key (upper Keys, Fig. 42B). Coral cores are 2.54 or 7.62 cm (1 or 3 in.) in diameter, depending on the size of core barrel used. After the core is removed, the top of the hole in the coral head is plugged with a numbered cork-shaped plug made of underwater cement. A healthy coral will overgrow the plug in a few years, so, for future reference, care must be taken to note precisely which corals in a reef or patch reef have been cored.

Printable Version (1.2 MB PDF)

Can't see the printable PDF version? Get the free Adobe Acrobat® Reader.

Coastal & Marine Geology Program > Center for Coastal & Watershed Studies > Professional Paper 1751