250 BULLETIN OF THE 



the steeper bluffs are thickly coated with" tepetate," or tiifaceotis deposits. 

 Great caverns abound in these rocks in many parts of the island. 



These limestones have been so greatly altered since their original 

 deposition that, from macroscopic examination, it is difficult to tell their 

 original character or the conditions under wliich they were deposited. 

 They certainly do not anywhere exhibit the enormous proportions or 

 abundance of coral remains so apparent in the reef rock, nor do they 

 show, except occasionally, an abundance of casts and moulds of molluscan 

 shells, and I seriously doul)t whether, as alleged by Crosby ^ and Kimball,'^ 

 and formerly by A. Agassiz,^ they are coralline in origin, as in the modern 

 reef rock. They sometimes contain traces of coral, but I do not think this 

 proves that they were reef rock, for all corals are not reef building, and 

 the organic remains are far more abundantly molluscan than coralline. 

 Neither can they be called chalks, although very foramiuiferous in places, 

 for they are too coarsely crystalline, clastic, and molluscan, and lacking 

 in that fineness and uniformity of texture seen in the chalky limestones, 

 which I have had considerable experience in studying. In places at their 

 basal contact they are certainly detrital, showing (as at the reservoir 

 south of Havana, where they are in contact witli the older series of clays 

 and serpentines) a distinct conglomeratic structure, and being compdsed 

 largely of shell fragments and beach wash. Near Villa Clara they contain 

 very small fragments of igneous material derived from the older rocks 

 which they buried. In many places they are distinctly sedimentarv, as 

 seen in the Castillo Principe Plateau west of Havana, where tliev con- 

 tain alternations of stratified, slightly yellow argillaceous layers, while 

 the several hundred feet exposed in the caiion of the Rio Armendaris, 

 south of Havana, exhibit far more molluscan remains than coral, although 

 some corals are present. Likewise at Matanzas the older limestones ex- 

 hibit every character of sedimentaries with molluscan remains, rather 

 than coral reef structure. At Baracoa, Nucvitas, and elsewhere on the 

 west coast, tlie limestones not only appear to be sedimentary, but they 

 alternate with beds of a yellow argillaceous and arenaceous material, 

 clearly sedimentary, and containing great numbers of molluscan fossils. 

 In fact, I do not believe that any of the limestones below No. 2 of the 

 Matanzas section (Plate II. Fig. 4) are of reef rock origin, but am of 

 the opinion that they are mostly organically and chemically derived sedi- 



^ On the Elevatefl Cora] 'Reefs of Cuba. Proceeilings of the Boston Society of 

 Natural History, Vol XXW. pp. 121-129. 



2 American Journal nf Science, Tlccemher. 1SS4. 



8 Bull. Mus. Comp Zo<iI., Vol. XXVI. No. 1, December, 1894. 



