We investigated one site in the Tyrrhenian Sea, one in the Balearic Sea, and four in the Alboran Sea during Leg 161. Neogene nannofossils are generally abundant and mostly well preserved at all sites. The following Neogene sections were recovered: a complete upper Miocene (Zone NN11) to uppermost Pliocene (Zone NN19B) sequence in Holes 974B and 975B; middle Miocene (Zone NN7) to uppermost Pliocene in Hole 976B; middle or upper Miocene (Zones NN7-NN11) to uppermost Pliocene in Hole 977A; middle Miocene (Zone NN11) to uppermost Pliocene in Hole 978A; and middle Pliocene (Zone NN16A) to uppermost Pliocene in Hole 979A. Several hiatuses exist in the upper Miocene and Pliocene in Holes 976B, 977A, and 979A.
The changing downhole ratio of cool-water Coccolithus pelagicus to warm-water Discoaster brouweri indicates a relatively cool period during the early part of Zone NN12, a warm period during later NN12-early NN13, and another cool period during late NN13. Generally warm conditions prevailed during Zones NN15, NN16A, and NN16B, with the warmest waters of the Pliocene occurring in Zone NN16B. A dramatic cooling began by Zone NN18.