e 
of the Specular Iron-Ores of Santiago de Cuba. 419 
Along with a study of some very remarkable deposits of a 
specular ferric oxide, in course of development by the Juragua 
Iron Co. (Lim.), for consumption in Pennsylvania, these hills 
came under my observation in the months of June and July last. 
s here distinguished, they consist of two parallel ranges of 
foot-hills distinct from the immediate south flank of the Sierra 
Maestra. The first or upper range reaches an elevation of 
case of the lower range, well into the syenyte. The syenyte 
base of the upper range is occupied by the bed of the Carpin- 
tero, and that of the lower range by the Juragua and its east 
fork—the Benevolencia. 
he lower contact of the dioryte mantle with the syenyte 
base of the Sierra (according, first, to unequal elevation and, 
second, to subsequent unequal erosion), follows a convoluted 
line. This contact corresponds, as elieve, to parts of a 
former coast line, as shown by traces of ancient corallines. 
These traces are as follows: 
1. Isolated bodies of marble without stratification, but with 
marked prismatic cleavage. These invariably occupy the ele- 
vated parts of the contact. 
2. Isolated bosses and other bodies of specular and amor- 
phous ferric oxide, only partially dehydrated, which I take to 
be replacements of ancient corallines. ‘These occupy the lower 
parts of the contact. 
Referring both occurrences to their original relations to the 
coast, they seem to be relics of bodies of coral rock and of coral 
ree! reposing on the syenyte. ‘These masses became implicated 
in the igneous overflow, one or more than one, from the north. 
This is shown by the approximately east and west direction of 
the longer axes of them all. The upper ones, or those now 
occurring as marble, were probably of the nature of emerged 
coralline, while those occurring as ferric oxide, lower in posi- 
tion and farther to the south, were. probably of the nature of 
coral-reef when involved in the eruptive flood. These are 
found directly back of the lower contact, while the bodies of 
marble, in a similar relation to the contact, appear to be farther 
ack of it. 
The thinning of the dioryte mantle toward the sea is thus 
seén to have been not altogether the result of its flow, slacken- 
Ing as may be supposed inversely to its mass, but to have been 
promoted by the extinguishing effect of the sea. The sea 
Seems also to have brought the flow to a stop. 
o traces of ancient coral reefs have been observed between 
