1913.] NATURAL SCIENCES OF PHILADELPHIA. 605 



same formation. It contained the Orbitoides antl many fragments of 

 echinoids, and furnished a recognizable Scala, referred to below. 

 Spencer^^ remarks of these sandstones that "one suspects the Hodge's 

 Hill sandstones belong to an epoch not long subsequent to that of 

 the former rocks" (Antigua limestones); a conclusion in which I 

 certainly concur. In fact, it seems more than probable that thej^ 

 are only the continuation upward of this same Antigua formation. 



6. Friar's Hill Gravels and Marls (of Spencer). 

 An undoubted unconformity, representing a break in the deposi- 

 tion of the formations lasting through the Miocene and Pliocene, 

 separates these gravels and marls from the Oligocene of the Antigua 

 formation. These deposits of Friar's Hill rest upon the eroded sur- 

 faces of the Antigua limestone, and consist, at the. base, of water- 

 worn pebbles, derived from the underlying formations; and this 

 layer of pebbles is overlaid by a compact, buff-colored marl stated 

 by Spencer to have a thickness of about 12 feet, and doubtless likewise 

 derived in large part from the underlying marl itself. The material 

 seems to be always not greatly different from the underlying marls 

 of the Oligocene, as though derived in each case from rock in the 

 immediate vicinity. Spencer, also, notes that the material does not 

 seem to have been transported to any distance. I am inclined to 

 think it should be connected with the Cassada Garden gravels as the 

 shore deposit that was formed during this depression of the island 

 when the shell beds of the Central Plain were being laid down, and 

 the Cassada Garden gravels are the current-transported materials of 

 the same general age. I have not seen these Cassada Garden gravels 

 overlying the Friar's Hill deposits, and at Cassada Garden the 

 gravels rest upon the tuffs under the Antigua formation. No fossils, 

 except those that are derived from the marls, are found in the Friar's 

 Hill deposits, but, up to at least 150 feet above sea level, the shells 

 of the next division cover the ground in the region of the Central 

 Plain. The Friar's Hill gravels, according to Spencer, occur up to 

 200 feet above sea level, while I have traced the shell deposits of the 

 Central Plain (as above stated) up to at least 150 feet above the 

 sea level. 



7. Shell Beds of the Central Plain. 



Throughout the Central Plain of Antigua, from the neighborhood 

 of St. John's to Willoughby Bay, sea shells are encountered in the soil 



14 Quart. Jour. Geol. Soc. London, Vol. LVII, 1901, p. 499. 



