HILL: GEOLOGY OF JAMAICA. 215 



relations of these beds in Jamaica indicate a later age. Deferring to 

 Ball's opinion, I have tentatively accepted his conclusions, however, 

 until more field work can be done. 



This subsidence was the first of the group of oscillatory movements 

 w^hich succeeded the great Mid-Tertiary Antillean orogenic displacement, 

 and which in succeeding cycles apparently became gradually more epeiro- 

 genic in character and successively of decreasing amplitude. While these 

 movements in late Tertiary, Pleistocene, and recent time were far reach- 

 ing and apparently of uniform character over wide fields of extent, they 

 were rather of the nature of great swells or wide gentle folds, with 

 movements of opposite direction in their ultimate extension, and of a 

 nature which cannot as yet be completely harmonized with those of 

 our Atlantic Coastal Plain. Furthermore, while in some epochs the 

 records of these movements are most clear and unmistakable, there 

 are others which it is exceedingly difficult to interpret, and hence their 

 analysis as a whole is sometimes obscure. 



Since the dismemberment of the Antillean lands through subsidence, 

 the aggregate of the upward movement has not been sufficient to restore 

 the islands to the heights they occupied during the orogenic expansion. 



We have described with some care the various topographic levels which 

 make great benches around the mountainous nucleus of Jamaica, and 

 record phases in the physical history of the island. These levels prac- 

 tically belong to three great groups, the oldest of which are from 1,500 

 to 2,000 feet above the sea, and which may be called the Junki type ; 

 the next oldest, from 100 to 1,000, which may be called the Yumuri 

 type ; and the newest and most recent less than 100 feet. In a previous 

 paper I have shown that these old levels are practically traceable around 

 the island of Cuba, especially its eastern end. I can now add that they 

 are also similarly developed on the island of Haiti. There can be but 

 little doubt that these three series of terraces are characteristic of the 

 Great Antilles adjacent to the Windward passage, while the two series 

 are more widely identifiable. These stair-like terraces may record re- 

 peated intermittent upward movements, or such movements alternating 

 with epochs of subsidence. I was unable to find in the geologic forma- 

 tions and structure any data to sustain the hypothesis of subsidence. 



It is difficult to establish the chronology of Post-Bowden events be- 

 cause paleontology has given us no positive key by which we can dis- 

 tinguish with exactness the formations of the Pliocene, Pleistocene, and 

 recent epochs. The calcareous Post-Tertiary material composing these 

 islands resolves into two distinct types : coral reef rock, and white lime- 



