A wide variety of lithified carbonates has recently been found in the deep sea of the equatorial Atlantic. These include partially lithified foraminiferal oozes, foraminiferal limestones, tuffaceous limestones, completely recrystallized limestones, and dolostones. No correlation was observed between paleontological age and degree of lithification. The close spatial association of such diverse carbonate rocks on the ocean floor appear to indicate very local variations in the geochemical conditions for carbonate lithification. The relative infrequency of reports of such rocks from the deep sea probably represents inadequate sampling rather than a real rarity of lithified carbonates in the upper suboceanic crust.