Biology (CMC), WM Keck Science (CMC), Biology (Pitzer), WM Keck Science (Pitzer), Biology (Scripps), WM Keck Science (Scripps), WM Keck Science
Magnetostratigraphic analysis of deposits exposed in Cueva del Aleman shows two reversed and two normal chronozones. The lower normal polarity event is observed in a clastic dike and probably predates initial cave formation. Sediments deposited inside the cave proper show a R-N-R sequence and probably date to at least 1.8 Ma. A fossiliferous clastic dike contains normal polarity with an overlying reversed magnetozone. Audubon’s Shearwater (bird) bones occur in the dike, which is tentatively correlated with the lower N polarity zone predating cave formation. If this correlation is correct, the Audubon’s Shearwater (Puffinus lherminieri) range can be extended back to at least 1.8 Ma, the Olduvai subchron.
Bruce C. Panuska, John M. Mylroie, Darrell Armentrout and Donald McFarlane. (1998). "Magnetostratigraphy of Cueva del Aleman, Isla de Mona, Puerto Rico." Journal of Cave and Karst Studies 60(2): 96-100.