The sediments drilled during Leg 14 of the Deep Sea Drilling Project off northwestern Africa and northeastern South America comprise a wide range of Cretaceous and Tertiary deep-sea facies. The major processes controlling the distribution of these facies are the changing patterns of supply and preservation of biogenous matter, terrigenous influx, and erosion and redeposition on the ocean floor. The sequence of mid-Tertiary to Quaternary sediments can be described as an evolution from a "north Pacific" to a typical "Atlantic" facies, contingent upon a change in deep-sea circulation from ascending (estuarine) to descending (lagoonal), and a decreasing orogenic influence. For older sediments, recent counterparts are not available in many cases, and the reconstruction of the ncient environments involves unfamiliar sets of geochemical, climatological, and geographic variables, in addition to diagenesis.

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