MUSEUM OF COMPARATIVE ZOOLOGY. 251 
ments of marine lime mixed with the-calcareous débris of the life of the 
ocean’s margin, with, in places, an almost imperceptible proportion of 
the finer physical sediments of the nucleal island. 
-While these limestones and alternating beds have a great areal extent, 
it would be a mistake to assign to them a proportional thickness, for 
accurate measurements will not make their thickness anywhere greater 
than one thousand feet. I estimated from the dips in the Rio Armen- 
daris section that they were from eight hundred to one thousand feet ; 
the incomplete section in the caiion of the Yumuri of Matanzas reveals 
eight hundred feet ; the canon of the Yumuri of Baracoa shows six hun- 
dred feet ; the summit of Yunque displays less than one thousand feet ; 
while the section from fourteen kilometers south of Havana to Bata- 
bano is not over one thousand feet. (Plate II. Fig. 1.) In fact, they 
may be said to constitute a comparatively thin veneering over the old 
metamorphic floor. 
The old limestone formations occur from end to end of the island, and 
extend in many places completely across it down to water level. Their 
continuity is interrupted only by erosion along the central axial region, 
and only the low portion adjacent to sea level is covered by later deposits. 
De Castro’s geologic map of Cuba? shows in an excellent manner their 
general disposition. In places, as between Mata and Yumuri, they form 
the north wall of the coast. They cap the highest eminences of the 
island seen by me, overlooking all other rocks, being overreached only 
by the Sierra Maestro, the geology of which is unknown. Their close 
proximity to the north coast and their abrupt protuberance above the 
newer formations have an important bearing en the history of the island 
- asawhole. So extensive is this old limestone formation, and so abruptly 
does it rise above the coast, that, if all the coastal formations were 
stripped away, or if the island should subside for one hundred feet, its 
superficial extent would hardly be perceptibly diminished or its outline 
materially altered. 
The greater part of these limestones seen by me are of Eocene and 
Miocene or of Pliocene age, as alleged by De Castro. In the Armendaris 
section, near Havana, they are both Eocene and Miocene, as has been 
asserted by De Castro and others, and as is shown by my collections.” 
1 Croquis Geologica de la Isla de Cuba, por D. Manuel Fernandez de Castro, 
ampliado por D. Pedro Sallerain y Legarra. 1869-83. Printed in Vol. IX. of the 
Congreso Internacional de Americanistas. 
2 The determinations of age in this paper are based upon the paleontologic 
determinations of Dr. William H. Dall, of the U. S. Geological Survey, who kindly 
examined the material collected. 
