178 GEOLOGICAL RECONNAISSANCE OF THE DOMINICAN REPUBLIC. 



The salt in the ground immediately adjoining these wells appears to have 

 been washed out, and if the wells had been energetically pumped the salt 

 might have been removed much more quickly. 



Though the wells are shallow and inadequate, enough of them have been 

 sunk to show that ground water can be obtained in the lower part of the 

 valley of Rio Yaque. The porous beds in the underlying rocks form a large 

 reservoir for the storage of ground water. The drainage from the well- 

 watered region about Santiago and from the Cordillera Central furnishes an 

 ample supply of water to fill this reservoir. Wells sunk almost anywhere 

 in the lower part of the Yaque Valley would probably strike water, and a 

 permanent supply might be obtained by pumping wells that penetrate the 

 permanent water table. The quantity of water obtainable would be ample 

 for domestic use and it might be sufficient for irrigation. 



Definite statements concerning the mineral content of the water from 

 such wells are unwarranted. The water obtained in shallow wells that 

 have been dug is at first invariably salty, but several of the older wells now 

 yield potable water. Most of these wells have been sunk in the alluvium, 

 but several were dug in Miocene rocks. Evidently salt is present a short 

 distance below the surface in both the alluvium and in the older rocks. 

 In some places the salt appears in salt flats on the surface. The presence 

 of potable water in some of the old wells shows that the salt in the soil or 

 in the rocks near these walls is rapidly removed. If modern pumping 

 methods were applied the salt might be removed even more rapidly and 

 effectively. As many of the Miocene rocks arc calcareous the water in 

 some of the deep wells may be too hard for use in the laundry. Water 

 obtained from the crystalline rocks near Dajabon would have a much 

 lower mineral content. 



POSSIBILITY OF OBTAINING ARTESIAN WATER. 



The well-watered region of the middle part of the Yaque Valley and the 

 part of the Cordillera Central that bounds the area on the south would 

 evidently furnish an adequate supply of ground water, and as these areas 

 are considerably higher than the lower Yaque Valley the water would be 

 under adequate pressure, yet the information obtained does not warrant 

 definite conclusions as to the possibility of obtaining artesian water in the 

 valley. As older Miocene rocks dip from the south northward under 

 younger rocks in the upper and middle parts of the Yaque Valley and pass 

 below the rocks exposed around Monte Cristi, and as the valley floor slopes 

 toward the mouth of the river, underground water from the middle parts 

 of the valley might drain into the Miocene beds that underlie its lower 

 parts. However, as the Miocene strata of the lower valley are faulted 

 against the foothills of the Cordillera Central, the quantity of water that 

 enters the Miocene strata may not be so great as might enter if the strata 

 were upturned along the mountain front. 



