166 
8E0L0GT OF CUBA. 
cayems m which the pluvial waters accumulate, and where 
small rivers disappear, sometimes causes a sinking of the 
earth I am of opinion that the gypsum of the island of 
Luba belongs, not to tertiary, but to secondary soil ; it is 
work'-i. m several places on the east of Matanzas, at San 
Antoi i de los Banos, where it contains sulphur, and at the 
Oayos, opposite San Juan de los Eemedios. We must not 
confound with this limestone of Guines, sometimes porous, 
sometimes compact, another formation so recent, that it 
seems to augment in our days. I allude to the ealeareons 1 
agglomemtes, which I saw in the islands of Cayos that 
border the coast between the Batabano and the bay of 
Xagua, principally south of the Cienega de Zaiiata, Cayo 
Buemto, Cayo Flamenco, and Cayo de Piedras. The sound- 
ings prove that they are rocks rising abruptly from a bottom 
ot between twenty and thirty fathoms. Some are at the 
water s edge, others one-fourth or one-fifth of a toise above 
the smlace of the sea. Angular fragments of madrepores, and 
cellulana from two to three cubic inches, are found cemented 
by grains of quartzose sand. The inequalities of the rocks 
arc covered by mould, in which, by help of a microscope, we 
only dishnguish the detritus of shells and corals. This 
totiary fomation no doubt belongs to that of the coast of 
Oumana, Carthagena, and the Great Land of Guadaloupe, 
noticed m my geognostic table of South America.* MM. 
Lhamiso and Guiamard have recently thrown great light 
on the formation of the coral islands in the Pacific. At 
the foot of the Castillo de la Punta, near the Havannah, 
on shelves of cavernous roeks,t covered with verdant sea- 
* M. Moreau de Jonnes has well distinguislied, in his Histoire phy- 
sique des Antilles Francoises, between the “Roche a rarets” of Martinique 
and Hayti which is porous, filled with terebratulites, and other vestiges 
ot sea-shells, somewhat analagous to the limestone of Guines and the wl- 
careons pelagic segment called at Guadalonpe “Platine,” or “ Maeonne 
Rev V dM Re ’MR* “rf ’ ‘1’® " J“fdinaio’s del 
wX/ fn , 1 'ying above the surface of the 
hX vI “® *“ frag'oontery, that is, composed of broken 
-- 
t The surface of these shelves, blackened and e.vcavated by the waters, 
presents ramifications like the cauliflower, as they arc ob.served on the 
currents of lava. Is the change of colour produced by the waters owing 
