282 BULLETIN OF THE 
Ill. RESUME AND CONCLUSION. 
The known geologic history of Cuba may be stated as follows : — 
1. In Pre-Tertiary times an old land existed, almost as extensive in 
area as the present island. Whether this old land was insular, multi- 
insular, or connected with other Antillean areas or the mainland, I will 
not speculate. The submarine topography indicates that it was not. 
Its composition and structure, however, show that it was an area of 
active vulcanism accompanied by great metamorphism and eruptive 
flows. If there are preserved in it any traces of Pre-Tertiary sedi- 
mentation they are largely overwhelmed and almost obliterated by the 
vulcanism, metamorphism, and later erosion. Paleozoic, Triassic, Jurassic, 
and Cretaceous sediments have been reported by De Castro? in localities, 
but their physical history is unknown. 
2. It is also certain that during Tertiary times, embracing the Eocene 
and Neocene periods, this ancient nucleal land, with all of its geographic 
outlines, completely subsided beneath sea level, and that it was covered 
with limestone sediments, which were organically derived from the sea, 
not the island itself, for there is no semblance of limestone material in 
the rocks of the Pre-Tertiary land which could have furnished material 
for the Tertiary rocks. That this subsidence was profound we may 
reasonably conclude from the thickness of the older nucleal region, now 
visibly covered by the limestone beds, which have been horizontally ele- 
vated to a height of at least two thousand feet. In other words, the 
Pre-Tertiary subsidence may have been at least to an equal depth. 
During this epoch of Tertiary subsidence a thousand feet of Tertiary 
limestone were accumulated over the old nucleal island. 
3. After the close of Tertiary times the Tertiary sediments were 
greatly warped and folded, concurrently with an emergence of the land 
from the sea. This movement was orogenic. 
4. Following this began the epoch of epeirogenic or regional elevation. 
During Pleistocene time the island underwent the first of these upward 
impulses to its present height, with the exception of about six hundred 
feet represented in still later movements. This older Pleistocene or 
Yunque elevation raised the main area to a height of at least two thou- 
sand feet in its eastern half, and fifteen hundred feet in its western half. 
How much higher it extended we cannot tell, so great has been the 
erosion. This elevation was so rapid and general throughout the island 
1 Op. cit. 
