198 



OjST the topograph y and geology 



menced, but soon abandoned, and the rusting' tools and a broken engine lie scattered 

 around. The tube of the well is filled with oil and water through which an inodorous 

 and non-inflammal)le gas bubbles to the surface, ^fear the well there is a shallow 

 depression on the hill side entirely bare, probably from the escape of the same gas, 

 which seems to be deleterious to vegetation. It, however, does not affect the surface 

 beyond the margin of the depression, which is simply a little basin a few feet deep 

 and a dozen yards across. The spot is interesting, mainly because it is the only one 

 where this mineral occurs in Santo Domingo. The Jamaican geologists do not men- 

 tion it, while Taylor,* as quoted by the geologists of Trinidad, says "the entire chain 

 of the West India and Windward Islands present similar phenomena of petroleum 

 springs, beds or veins of asphaltum and accumulations of mineral pitch," mentioning 

 particularly Cuba and Barbadoes. The last-named authors also quote deposits in ^^ew 

 Grenada, while the extensive outflows of Trinidad are perhaps without a parallel. 

 Schomburgkf also describes in detail the petroleum springs of Barbadoes, which 

 although not numerous seem to be of large size. 



Beyond Azua our knowledge of the geology is necessarily very limited. Both 

 Mr. Pennell and I made excursions as far to the northwest as Tubanos on the Con- 

 stanza trail, and that gentleman penetrated eastward from this route some distance up 

 the river of las Cuevas, and made a boat excursion to the southwest alouij the coast 

 to the boundary at the north of the Rio Pedernales. ^ . 



I have already described the sierra slates as extending to Tubanos, where they 

 finally disappear under the Post Pliocene beach deposit. Further back in the hills, 

 however, just below las Lagunas, these gravels elevated a couple of hundred feet lie 

 horizontally or with an almost imperceptible southern dip, on the upturned 'edges of 

 the slates and are cut through by the canon adjoining the road. This portion of the 

 deposit contains boulders often more than a foot in diameter, derived fiom the ISTeyba 

 or Southern Yaqui River. It spreads all of the width of the San Juan Valley to the 

 base of the mountains on the other side, and must be found at least as far up as the 

 town of San Juan. Just west of this town there is a little " divide," beyond which 

 the streams run into the Artibonite. My hearsay information in regard to what lies 

 beyond is too unreliable to be recorded here. Suffice it that all evidence unites in 

 representing the valley as the best grazing land iu the Island, an evergreen plain, a 

 continuous prairie of " Gruinea grass " that never suffers from either droughts or 

 floods. What underlies it we do not know. From Tubano the same gravels extend 

 southeast, reinforced b}^ the supplies derived from the Rio de las Cuevas, and cover 



* statistics of Coal, p. 247. 



•f- History of Barbadoes, pp. 553 and 571. 



