MUSEUM OF COMPARATIVE ZOOLOGY. 257 



Quarries of cantera are found adjacent to most of the cities on the 

 north coast of the west half of the island. They occupy a slightly 

 higher altitude than the coast reef, and usually constitute the first 

 bench of the island above it at a lower level than the erosion planes in 

 the older limestones. (See Havana and Matanzas sections, Plate I. Fig. 

 1. 2, and Fig. 4. 1.) 



I did not observe any break between the cantera and the older lime- 

 stone, owing to obscurement, except in the Matanzas section, where it 

 clearly appeal's that the cantera is mostly old reef rock which has no 

 topographic integrity, antl which was unconformably deposited on the 

 older limestone after the latter had been considerably elevated. In other 

 words, it there represents the oldest of the recognizable fringing reefs. 



At Havana, in the convict quarry, northwest and at the foot of the 

 Castillo Principe Plateau, which is made up of the older limestone, there 

 is a great cantera that seems more molluscan than coralline. The same 

 deposit is also- worked in the banks of the Piio Armendaris, two or three 

 miles southwest. Topographically it here underlies an erosion level 

 intermediate in heipht between the level of the modern reef and that of 

 the Moro Plateau.^ Xo cantera was observed east of Matanzas in the 

 ports of Segua, Gibara, Nuevitas, or Baracoa. It is not here proposed 

 to establish the cantera as a persistent geologic unit, for tliere may be 

 other cantera beds in the old limestone. The coralline cantera of Ma- 

 tanzas and the molluscan cantera of Havana are not found at an alti- 

 tude of more than one hundred feet, and they are always near the coast. 

 At the furmer locality the cantera is the oldest of the rocks of prob- 

 ably coralline origin, and at the latter it is intermediate in position 

 between the modern reef rock and the older limestone. 



Throughout Spanish America the term " playa," meaning literally 

 a flat beach, lacustral, or shore deposit, is applied to alluvial flats or 

 mud plains composed of gravel, sand, and clay. In Cuba I found that 

 the term was generally used for an alluvial deposit sometimes lining the 

 inner margin of the circular harbors, as at Havana and Baracoa. These 

 are small in area, and are usually adjacent to the zone at which tlie 

 rivers come out of the highland into the harbors ; they represent delta 

 deposits that have undergone slight elevation coincident with that of the 

 modern elevated reef Their origin is more fully discussed under the 

 head of Harbors. 



^ Specimens of this cantera received from Havana since tliis report was written 

 soniewliat eonfirni tlie impression that they represent a late Post-Pliocene deposit laid 

 down aijainst the ohier Tertiaries, and prior to the elevation of the soboruco. 

 VOL. XVI. — NO. 15. 17 



