66 GEOLOGICAL RECONNAISSANCE OF THE DOMINICAN REPUBLIC. 



Section of Yaque group (Miocene) near Quito, Coraza. 



Thickness 

 in meters. 

 5. Sandstone, coarse to conglomeratic, with shaly beds in the 



lower part; light olive to gray. Large Areas and other 



fossils plentiful in the lower beds 600 



4. Clay-limestone member; calcareous, containing branching 



corals and layers of limestone filled with fossils (station 8590) 200 



3. Sandstone, conglomeratic 100 



2. Shale, bluish with thin sandstone laminae; no fossils seen 400 



1. Sandstone and conglomerate, bluish sandy shale, and thin, 



nonpersistent beds of limestone; some of the beds contain a 



few fossils, chiefly fragments of branching coials and 



oysters 1500 (?) 



Lists of fossils collected from the Yaque group on the south side of the 

 Cordillera Central are given on pages 155-162. 



BAITOA FORMATION. 



The Baitoa formation is named from a village on Rio Yaque del Norte 

 on the road from Santiago to Jarabacoa. The formation at the type 

 locality is a conglomeratic sandy marl containing an abundance of fossil 

 shells. It rests with marked angular unconformity upon the upturned and 

 beveled edges of the Tabera formation. Its upper limit has not been as- 

 certained, but it is probably conformable with the Cercado formation. At 

 Baitoa it dips gently northward. It is exposed in the bluff at Baitoa for a 

 thickness of probably about 30 meters, but it may be considerably thicker. 



The formation is best exposed in the high, horseshoe-shaped bluff on the 

 right bank of Rio Yaque just below Baitoa, where it forms a nearly vertical 

 cliff at the top of a very steep slope composed of blue-gray shales, sand- 

 stones, and conglomerates of the Tabera formation. The older formation is 

 steeply tilted 40° toward the northeast and strikes N. 40° W. Upon the 

 truncated edges of the dark strata of the Tabera formation lie the gently 

 sloping, rusty-yellow conglomeratic sand and marl of the Baitoa formation. 

 Even from a distance the contact is clearly visible, for the contrast between 

 the formations is striking. The vertical climb of nearly 50 meters from Rio 

 Yaque to the base of the Baitoa formation is difficult, and in many places 

 it is impossible. The formation is more conveniently examined along the 

 trail leading from Baitoa to Santiago, which passes up the hill and along 

 the edge of the cliff, but the exposures here are poor and the fossils are not 

 so abundant. 



The fossils named in the lists given on pages 113-114 were collected 

 from the Baitoa formation. 



BULLA CONGLOMERATE. 



The Bulla conglomerate, which is named from a village on the west side 

 of Rio Mao near the crossing of the trail from San Jose de las Matas to 

 Moncion, rests with depositional contact upon schistose sediments of the 



