hill: geology of JAMAICA. 



163 



These movements have collectively constituted the great oscillations 

 whereby, since the close of Cretaceous time, the land and sea bottom have 





Figure 39. Coast Benches, Trelawney. 



moved up and down, resulting in the expansion or shrinking of the re- 

 respective areas in harmony with these movements. 



OSCI LLATION5 



JAMAICA 



Figure 40. — Changes of Level in the "West Indian Region. 



These oscillations, as summarized upon the accompanying diagram, 

 have comprised three complete cycles of movement, each of which em- 

 braced a period of depression and elevation, the downward movement 



