* OF SAXTO DO^JIXOO. ] ;l;3 



surface of the underlying rock, Tliey continue thus almost to Ciuaraguano, and the 

 top layers are always the same coarse sandstones, from which I have collected eight 

 species of mollusca, all of which are common in the blue shale. 



Down the Mao below Hato Viejo, where the river cuts through the Samba range, 

 we have a section which is practically a repetition of that on the j^mina, except that 

 here the gravels overlie the shale. The section is an instructive one, as illustrating 

 the relation between the gra^•el and the other members of the formation. The dark 

 shale with its characteristic fossils forms the base, becoming lighter in color towards 

 the top. Over it is the gravel, in this case unmistakably conformable, and above 

 this the beds of claystone, described as capping the hills east of i^aranjo, but here 

 more calcareous, form the sunmiit. These last beds, which in some places are in- 

 terstratified with the upper part of the gravel, become more calcareous northward, 

 and are really the ecpiivalent of the limestones of the Monte Ciisti range and Cevico. 



Beyond the hills of the Mao this gravel widens out westward and covers nearly 

 all of the little interior valley behind the Samba Hills. It covers the rolling plain to 

 the Gurabo, and is there again seen on the margin of the hills overlapping the 

 Cretaceous exactly as at the Angostura of the Mao. Whei"e the Gurabo passes the 

 Samba Hills the same section is repeated, with the trifling local variation that the 

 dip is about 15° to the north. I here collected some species of fossils not found further 

 east, and Mr. Bonaczy o])tained for me a fine series, including many of the large' 

 Cassis, which is quite rare elsewhere. One may here tire himself picking up cones 

 of a dozen species which weatlier out from the bluff by hundreds, and T'leurotoma, 

 Fusus, Turhinella are almost as well repi-esented, while the other shells, though not 

 so numerous, are still so abundant that literally a good collection may be made here 

 in a few minutes for the mere ti'oublc of ])icking it u]). 



The lower part of the Rio Canna, the next stream west, yields fossils ; but the 

 cxposui'e, while showing no new facts, is much less important than the pi"€ceding. 

 Its course before reaching the hills is across the low rolling plains of the Mao gravel, 

 which is here horizontal, and is underlaid by the brownish sandy shales so often 

 referred to occmring near Guayubin and elsewhere. In some places these underlying- 

 shales are exposed in the bed of the stream. The back or southern boundary of the 

 gravels is reached approximately where the stream issues from the foot-hills of the 

 main range, the road crossing it in the slates. 



From the crossing of the Cannn to Savaneta there is a flat i)laiu of beautiful 

 ])rairie, with little rolling hills, the whole interspersed with groves or open growth of 

 trees and a little cactus. It is underlaid by hori/.(Mi!;d beds of the same gravel, in 

 A. r. S. — w. ^M. 



