Pisco Formation exposed in Cerro Blanco (foreground) and Cerro Baleena (background). Notice lack of vegetation, and well-exposed stratigraphy, because there is no rain. This made it easy to find fossils and study the sediments, and facilitated accurate determination of the stratigraphic position of fossils. There has been only limited tectonic activity here after deposition of the Pisco Fm., which facilitates determination of the original Miocene/Pliocene paleogeography. The lower part of these hills (steeper slopes) is largely sandstone with some diatomite, and the upper part (containing most of the whales) is mostly diatomite.
Completely articulated fossil whale, except for one missing flipper, on Cerro Blanco. Front of skull damaged by modern erosion. Otherwise the bones are very well preserved.
Distribution of fossil whales on Cerro Blanco, superimposed on an aerial photo. Red dots = individual whales (N = 180). Black dots = specimens that cannot be determined to be complete whales, usually because of post-exposure erosional damage (N = 166). It appears likely that most whales were essentially complete before the effects of modern erosion processes.