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HILL: GEOLOGY OF JAMAICA. 
PART VI. 
APPENDICES. 
I. 
ADDITIONAL NOTE ON THE GEoLOGY or Porto Rico AND SANTIAGO 
DE CUBA. 
Sınon the foregoing pages were placed in type I have made a geologi- 
cal reconnoissance of Porto Rico and Santiago de Cuba. In the former 
island I found the general Antillean sequence, but modified by certain fea- 
tures hitherto known only in the Caribbean chain : — 1. An older plexus 
of water-sorted hornblendic volcanic material, — tuffs and conglomerates 
with interbedded Cretaceous Rudistean limestone similar to that of 
Jamaica, composing the central mountains. 2. An Eocene system of 
impure lignitic sands and clays like the Richmond beds, occurring on the 
western side of the island near San Sebastian. 3. Fossiliferous marl 
beds overlapping the above, which at this writing have not been deter- 
mined. 4. Miocene coral limestone, unlike anything hitherto recorded 
from the Great Antilles, but of the type occurring in Antigua. These 
constitute the hilly country north and northwest of Lares. 5. White 
limestones of probable Pliocene ago, composing the hills of the south 
coast. 6. Elevated reefs, but feebly represented. 7. Alluvial plains 
of Pleistocene age. The terrace phenomena are less developed upon 
this island than in any of the other Great Antilles, although the Pleisto- 
cene base-levelling is well developed in stream valley phenomena. Dikes 
of syenitic-like porphyry, probably diorites, were also noted cutting the 
older hornblendic rocks. 
Evidenco was obtained indicating that the greater mountain move- 
ment culminated before the Miócene, and that there has been at least 
one thousand feet of vertical uplift since that epoch. 
VOL, XXXIV. 15 
ames Samen 
