In February 1966, Exxon Corporation undertook a geophysical and geologic survey of the continental slope of the Gulf of Mexico from Texas to Florida. They were joined in May by Standard Oil Company of California and in August by Gulf and Mobil Oil Companies.

As part of this survey the Caldrill 1 was to drill 42 coreholes at 36 sites. Submarine current measurements were to be recorded while the vessel was on station. Because of technical difficulties, submarine-current records were obtained at only 6 northwestern sites.

Vertical current profiles at 5 of the 6 stations show two prevailing directions which may represent distinct water masses. The upper current flows generally east or northeast, increasing from about 0.2 knots in the west to about 0.4 knots in the east. Below this system is a current that flows west or northwest at similar rates. The interface between these water masses deepens

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westward, from about 400 to about 600 m. The deeper mass may be related to the Yucatan Current.

At 5 sites the meter was maintained for up to 9 hours a short distance off the sea floor to determine the sustaining nature of the currents. Records obtained at 3 locations are consistent in both velocity and direction with the short-term measurements.

These few scattered measurements would not seem to warrant broad conclusions regarding the movement and structure of the water masses over the upper continental slope. However, the data clearly document certain water movements in the spring of 1966. Most of these data are internally consistent, and the velocities are sufficient at times to transport fine to medium sand.

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