OF SANTO DOMINGO. 



179 



to the casual traveller that the limestones have disappeared, and the nearly continuous 

 savanas are a sure index of the presence underneath of the more porous earths, sands, 

 and gravels. In a formation thus varying in its lithological characters, of course the 

 transition fi-om one form to the other must be gradual, and an equally easy gradation 

 between pure forest and pure prairie is to be seen along the line of junction. The pure 

 limestone bears a continuous forest ; the uninterrupted grass region is as strictly con- 

 fined to the sands ; and where the underlying beds vary from an earthy limestone to a 

 calcareous sand or earth, there the country is clothed with a beautiful succession of 

 open glades separated by lines and clumps of trees. The boundary separating the 

 Savana from the coast deposit, may be defined as running, more or less, midway 

 between the coast and hills bending north around Higuey. The pretty little town of 

 San Antonio de Guerra, or Guerra as it is more generally known, lies in this line in 

 one of the innumerable prairies, the view cut ofl:' in every direction by the clumps 

 and "tongues" of timber which surround it. The softer impui'C limestone of this 

 part of the plain seems to be better adapted to the retention of surface water than 

 either the more compact but fissured coast rock on the one hand or the porous sand 

 and gravel on the other. This results in the existence of innumerable little ponds 

 and lakes, scattered in ever}^ direction, never large, but many of them perennial. 

 They add greatly to the value of the region for grazing purposes, because the streams 

 though reasonably abundant, are still widely separated, and many tracts would be 

 otherwise without water. The drainage of the hills unites into a few comparatively 

 large rivers which cross the plain in very direct lines to the sea, and the local rainfall 

 either sinks into the soil or drains ofi' immediately thi-ough usually dry channels. 



Adjoining the hills occasionally little outcrops of the Sierra slates peep up through 

 the soil, but they belong rather to the mountain region already described than to the 

 plains under consideration. In some cases, however, the rolling ground continues 

 miles from the base of the range proper, and usually more or less of the slates are 

 found wherever the surface is at all uneven. Five miles south of Monte Plata, I 

 found a little exposure in the bed of a rain-water channel, where the rock was a black 

 and green serpentinoid shale breaking into semi-lenticular masses by oblique cross- 

 cleavages and with all of the surfaces polished, resembling somewhat " slicken-sides." 

 West of this on the San Pedro road clay slates crop out in numerous places, altei"na- 

 ting with the often-mentioned red and white semi-talcose shales which never show a 

 positive stratification. The former, however, as well as could be determined from the 

 very small exposures, seem to always have a high southern dip. The same rocks 

 occur around and south of Yamasa, and the latter is not infrequently seamed with 



