108 



oisr THE ToroanAPHY and geology 



miles northwest of the city, has a depth of 158 feet, and one on the farm of President 

 Baez, distant perhaps a fourth of a mile is a dozen feet deepei', a difference duo to 

 undulations in the surface of the ground. 'Near the mouth of the'Rio de las Cuevas 

 northwest of Azua, where the gravel is seen lying on the upturned edges of the 

 Cretaceous shales, clean sections of about one hundred feet can he seen ; and in 

 Samana the gravel hills are all of two hundred feet high. It may therefore be safely 

 assumed that an average thickness for the whole deposit is not far from two hundred 

 feet, and in the limestone it may be even greater. 



The peculiarity exhibited by all of the wells in the coast limestone that at what- 

 ever elevation begun or wherever placed with reference to the coast, theii" bottoms 

 must always reach approximately the same level before reaching water, recalls forcibly 

 a similar circumstance noted by ^vTelson in the Bermudas and Bahamas in the same 

 formation.* That author explains that in those islands the calcareous rock is per- 

 meated by sea water, and that the surface waters float above the dense salt water, 

 which is distinctly affected by the tides. In Santo Domingo although the wells all 

 reach tide level, it does not appear that the sea water penetrates to any distance 

 inland, and although the wells nearest the coast are usually more or less brackish, it 

 seems that the sea acts only as a dam preventing the complete drainage which takes 

 place at higher levels. It is at least certain that the tides do not affect the wells 

 here, and even that at the house of General Cazneau, within a hundred yards of the 

 sea, shows no signs of their influence. 



Almost wherever it occurs the coast limestone is covered by a peculiar red soil, 

 neither very deep nor remarkably fertile though aided by the moisture of the trade 

 winds and the constant warmth of the tropics, it sui)})orts a dense forest vegetation. 

 This is without doubt derived ti'om the underlying rocks and is clearly the result of 

 their decomposition. JSTo further jDroof of this proposition is required than the fact 

 that at least in the Provinces of Santo Domingo and Seybo, that is to say, on the 

 whole south coast east of the I^izao River, the red soil and the limestone ai"e exactly 

 coextensive. I dwell on this fact because JSTelson notices the existence of a "red 

 earth " in the Bermudas, as making the oi-dinary soil of the islands,! and again in 

 his account of the Bahamas not only refers to it, but advances the theory that it 

 originates as a sort of guano. J I infer from the remark quoted in the subjoined note 



* Trans. Geol. Soc, Vol. 5, p. 130, and Quar. Jour. Geol. Soc, Vol. IX., p. 305. 

 \ Loc cU., p. 105 and Bahama Memoir, p. 308. 



X In speaking of a "red earth " from a cave in the Bahamas, on microscopic examination it "appeared as a mass 

 of insect remains, the rejectamenta of bats living in these caverns. Specimens of the earth from another part of the 

 same cave, however, were so much altered in character that they resenibk'd the Bermuda "icd earth," and aflbrdcd a 

 complete clue to the characters of thi.s substance." 



