The view this afternoon could not have been better framed, since guarding La Entrada we have Santa Margarita Island and Magdalena Island. These islands are important in Baja California Sur, since they contain excellent exposures of Mesozoic oceanic rocks, together with the Vizcaino Peninsula, this makes up three regions in which metamorphic rocks are found. These rock types or terranes are found no where else in Baja California Sur.
Behind the whales we watched was Magdalena Island, a great "ophiolitic complex" divided into three terranes: northern, central and southern. The southern Magdalena terrane consists of a faulted sliver of pillow basalt, green and red chert, argillite, unmetamorphosed conglomerate, mudstone and sandstone along the contact between the central and southern Magdalena terranes.
