Sedimentary rocks in southern Costa Rica range in age from Late Cretaceous to Pliocene, and consist of limestone, arenite, black shale conglomerate, lava flows, pyroclastics, and andesitic, basaltic, and gabbro-basaltic intrusives. Many beds contain Foraminifera. Large volcanic islands in the Pacific are postulated as the source of sediments deposited toward the north.

You do not currently have access to this article.