Multichannel seismic data and Deep Sea Drilling Project (DSDP) well information reveal a prominent erosional unconformity in the deep southeastern Gulf of Mexico. Corresponding to a 44 to 38.5 m.y. B.P. hiatus (middle to late Eocene) at DSDP site 540 (Leg 77), the unconformity was apparently produced by the bottom effects of wind-driven surface currents (paleo-Florida Current) and gravitational mass movements capable of scouring the slope. Intensification of these sedimentary processes may have been related to global cooling and a reported drop in sea level in the late Eocene, but it may also have been part of a complex global response to a postulated Paleogene meteorite impact.