MATAN2AS FORMATION. 



83 



These shells were found at an elevation of 150 feet above the sea, but 

 the formation occurs to an altitude of perhaps 450 feet. 



In the region of Sagua le Grande small remnants of the Matanzas lime- 

 stone are found resting upon the upturned and eroded surfaces of the 

 older formation, notably the Tertiary strata. This character extends 

 into the interior of Cuba. 



In the region of Cienfuegos the Damuji flows through a valley bounded 

 by hills 80 feet high. At Abreus, on that river, the formation is a chalky 

 limestone. Farther up the valley, at the Santa Lucia brook, Mr Mathew 

 found' a deposit of buff-colored marl containing remains of olive-bark 

 tree, two mangroves, a fern, a palm, etcetera. However, the formation 

 in this vicinity is very much concealed by tierra negra. West of Damuji 

 the erosion has exposed white pyramids of the formation standing out 

 in strong contrast to the overlying red loams. 



In the vicinity of Cienfuegos tlie Matanzas limestones are most promi- 

 nent in the plateau ridge which separates the bay from the sea. This 

 plateau is about two miles wide and 100 or 150 feet high and extends 

 for many miles as a coastal terrace. Along the canyon which forms the 

 outlet of the bay the strata dip at 2° or 4° southward. The terrace is 

 shown in figure 6. 



r*?*"'^'*^*'!^^:?^.^^?*?:, -. 



Figure 6. — View of Terrace {Matanzas Limestones') at Entrance to Xagua Bay. 

 The fort is situated on this terrace, with Trinidad mountains in the distance, viewed from 

 the west. (After Hydrographic Office chart.) 



In the region of Trinidad the Matanzas limestones fill the hollows in 

 the surface of the older Tertiary rocks which form the baselevel plain, 

 from 175 to 200 feet above the sea, upon which the city is built. Near 

 the mouth of the San Luiz, which eaters the sea three miles from the 

 city, corals aggregated in colonies are common in the limestone ridge 

 which occurs just back of the coast. The Matanzas limestones are not 

 known to exceed a thickness of about 150 feet nor to rise higher in Cuba 

 than 450 feet above the sea. The dip is everywhere at low angles toward 

 the coast. 



The Matanzas formation is provisionally included with the Pliocene 

 system, so that it would form its last member if all of the earlier were 

 not wanting in Cuba. This classification is based upon physical con- 

 siderations, as there is no sharp paleontologic grounds for separating 

 the Pliocene invertebrata from the Pleistocene. The long succession of 



XII— Bull. Geol. Soc. Am., Vol. 7, 1895. 



