OF SAXTO DOMmCO. 



95 



fine white mud wliicli now glistens in tlie sun on the top of tlie Monte Cristi range. 

 We have thus an ideal section as follows : 



White calcareous marl, north of Moca ; white or light brown limestone ( ' ' Tufaceous 

 limestone" of Heneken) ; light brown calc sandstone, San Lorenzo Bay ; gravels of 

 Mao and Savaneta ; limestone of Samana, San le Mar, Cevico and the north face of 

 the Samba Hills ; oyster beds of Samba Hills, south of Guayubin. 



400 FEET. 



Brownish or yellowish shale of Guayubin ; conglomerate of Angostura of the 

 Yaqui ; sandstone strata near Santiago ; dark blue shale of Santiago ; gray shale 

 with beds of sandstone of Rio Verde and in the hills north of Moca. 



800 FEET. 



Coarse gray sandstone with some conglomerate ; seen best in the hills south and 

 southeast of Santiago ; also in a few i^laces in the north range . 



600 FEET. 



These three members are so intimately nnited that their sej^aration is purely 

 arbitrary. Beds of sandstone are found in the shale; and beds of shale extend far 

 down into the lower member. "Very few if any fossils have been found in the sand- 

 stone, though the gravels of Angostura yield shells abundantly, in connection with 

 fragments of fossilized wood. The same species of fossils occur in all parts of the 

 series, and I have collected from a bed of sandstone at the very summit of the Mao 

 gravel a series of shells identical with those imbedded in the rocks of the "non- 

 fossiliferous sandstone" plain* east of Guayubin, and which are found abundantly 

 in the blue shale of the Gurabo, Amina or Verde. 



* All the information previously possessed in regard to the Santo Domingo Tertiaries was derived from a Mr. T. 

 S. Heneken, who sent to the Geological Society of London a valuable collection of fossils, which formed tlie basis of 

 some excellent papers by J. Moore, Geo. B. Sowerly ana Dr. Duncan. Unfortunately the notes accompanying the 

 specimens were not so valuable as the collection, and for the rex)utation of their author had better have been omitted. 

 It would be a thankless task for me to attempt to discuss in detail the paper ( Quart. Jour. Geol. Soc, vol. 9, p. 115, 

 et seq. ), which is the most extraordinary tissue of incorrect observations and i'alse deductions I have ever encoun- 

 tered. A reference to the sections accompanying this memoir will show that his "red sandstone " existed only in 

 his imagination. It seems to have been made up of tlie heavy beds of Miocene sandstone south of Santiago, which 

 however are gray, not red ; of the nearly horizonal beds of Mao gravel which cover the plains about Savaneta and 

 perhaps also of the low-dii^ping strata of metamorphosed cretaceous conglomerate near San Jose de las Matas. At 

 least I can find no better explanation after a two years' search. It is very certain that the strata forming the middle 

 of the valley, given in his sections as " non-fossiliferous red sandstone, underlying the Tertiary," are usually high up 

 in the series ; blue shales at Santiago, light-brown shales between Esperanza and Guayubin, and his "Tufaceous 

 -limestone " at some points south of the river I 



