GEOLOGY AND WATER RESOURCES NEAR MONTE CRISTI. 173 



The following section was measured on the steep, bare slopes of El 



Morro. A barometer was used to determine altitudes. The fossils are 



listed on page 154. 



Section at El Morro. 



Meters. 



8. Sandy porous limestone containing a few fossils (station 8774, at 



an altitude of 155 m.) 63 



7. Thin beds of limestone alternating with fossiliferous clay (stat'on 



8783) 1.5 



Unexposed 4 



6. Soft sandy clay 9 



5. Soft clay and impure limestone 25 



4. Thin-bedded layers of sandstone, clay, and 'mpure limestone, 



containing a few fossils (station 8782, at an altitude of 105 m.).. 40 



3. Buff to reddish fossiliferous calcareous sandstone (station 8773).. 12 

 2. Hard, porous, buff-colored fossiliferous limestone, weathering 



gray (station 8772) 18 



Unexposed 45 



1. Buff limestone conglomerate 1 



218.5 



The beds that form El Morro strike N. 80° E. and dip 5° NW. The 

 basal member of the above section is exposed at sea level about 600 meters 

 south of El Morro. Members 4 and 5 are not actually exposed, but 

 the lithology was determined from an examination of the surface debris. 

 Although the collection of corals from member 3 (station 8773) is too small 

 to warrant a definite determination of age, the other collections indicate 

 that the beds exposed on El Morro are of the same age as the Yaque group 

 of the middle part of the Yaque Valley. Sconsia laevigata (Sowerby), 

 which is confined to the Gurabo formation in the middle Yaque Valley, 

 was collected from member 7 (station 8783) . Dr. Maury 1 collected the 

 same species at this locality. 



Cross-bedded argillaceous sandstone and sandy clay are exposed on a 

 hill immediately west of Isabel de los Torres, in the Monte Cristi Range, 

 about 9 kilometers northeast of Monte Cristi. The beds strike N. 60° E. 

 and dip gently northward. No fossils were observed, but the beds resemble 

 those exposed on El Morro, both in lithology and in structural relations. 



Similar sedimentary rocks were observed at two localities on Rio Yaque. 

 Thin-bedded sandstone and limestone, which strike N. 45° E. and dip 

 20° SE., crop out a short distance downstream from the manager's house 

 on Manzanillo Plantation. Thin-bedded sandy limestone, which strikes 

 N. 60° E. and dips 20° SE., is exposed on the south bank of Rio Yaqueat 

 La Barca immediately upstream from the ferry landing. 



Thin beds of clay, sandstone, and impure limestone are exposed in many 

 cuts along the automobile road from Monte Cristi to Santiago. The gen- 



1 Maury, C. J., Bull. Am. Paleontology, vol. 5, p. 450, 1917. 



