IGO 



ON TITE TOPOGRAPTIY AND GEOLOfJY 



except that the heavy dark sandstones of Tabera are not reached. They dip under 

 the sources of the river. The bi-own shales and sandstones form most of the hills 

 from the Verde northward, with doubtless a little limestone on top from which the 

 corals were derived, although I never found it in place. Below this are gray and 

 blue shales, and at their base some sandy beds, all more or less abounding in fossils. 

 The bluff below the house of the Alcalde on the upper Yerde is the counterpart of 

 those in the Samba Hills on the loAver Gurabo, Mao, or Amina; and a similar but 

 smaller bluff on the upper part of the Punal shows an equally good exposure of the 

 blue shale with many sandy beds evidently well down in the series, where the numerous 

 and perfect fossils richly rewaixl the collector. - 



From the Rio Verde to the Camu the road is in part over a few low rolling- 

 hills of gravel, which cover the line of junction between the Tertiary and the meta- 

 morphic slates. This gravel is extremely local. Its oi'igin is evidently in the hills 

 directly west, but its age is not so clearly established. One little circumstance may 

 throw some light on it. The Verde Kiver is the onl}^ stream in this vicinity in which 

 gold is found, and the Verde could not, with the present configuration of the surfiice, 

 throw its debris over this area ; but during the era of the Mao gravels that would 

 have been possible, since the mouth of that stream was not far from the then shore- 

 edge of the deposit, which is also very slightly auriferous. I am therefore inclined 

 to suspect a synchronism between the two gravel basins, which, however, I am not 

 inclined to sustain as a positive determination. Were the gravel not gold-bearing, 

 or were there gold any nearer than the head of the Verde, I should not have even 

 proposed the hypothesis. . . . 



The road across the hill from Santiago so Moca differs but little from the first 

 pai't of the Vega road. Very soon after they separate, the Moca road leaves the hill;^ 

 and thence runs the i-emainder of the distance over flat plains of black muddy loam. 

 In the dry season this bakes and cracks in the sun, and is as difhcnlt for horses to 

 travel over as a rough rocky surface. The same may be said of the route from Vega 

 to Moca. Except that for a very short distance it runs over the margin of the base 

 of Santo Cerro, it is entirely in the loamy valley. Santo Cerro is, as it were, surrounded 

 by the two roads running outof A^ega and a third which unites the two on its northern 

 flank. It is a low hill running nearly north and south, the last spur of the range 

 jutting out into the valley. It has ah'eady been referred to in the topographical 

 description of the region, and nothing more need be said here of its position or the 

 beautiful prospect it commands. It is made up of the brown shales and the sand- 

 stones of the vicinity, here dipping a little higher than usual to the northeast. On 



