The island of St. Croix is underlain by strongly folded Upper Cretaceous rocks which have undergone low-grade regional metamorphism, gently folded unmetamorphosed Tertiary sedimentary rocks, and igneous intrusions with contact-metamorphic aureoles of Late Cretaceous or Early Tertiary age. The Mount Eagle Group includes all the Upper Cretaceous sedimentary rocks and is composed of two interfingering facies, epiclastic volcanic sedimentary rocks and tuffaceous sedimentary rocks, both deposited below wave base in a marine environment. A turbidite sequence more than 8000 and perhaps 18,000 feet thick of epiclastic volcanic sedimentary rocks called the Caledonia Formation (Campanian or older) consists of alternating thin beds of sandstone and mudstone with minor chert and conglomerate. The clastic grains are minerals and lithic fragments derived from keratophyre and spilite flows and tuffs of the Water Island Formation (Cenomanian or older) exposed on St. Thomas, St. John, and the British Virgin Islands. Sedimentary structures include graded, current, and convolute bedding; scour markings; load casts; and slump structures. Structures indicating current and slope directions confirm a northerly source ... (Abstract).