354 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VOL. V. 



(Figure 4, page 2,37), which is called tlie " Palisades;' with a length of 

 about eight miles. The depth of the water inside reaches to 60 feet. 

 Before the district sank subsequent to the post-Liguanea elevation, 

 Kingston Harbour was only a continuation of the Rio Cobre. When 

 the land was depressed so that the coast line occupied the location of 

 the eastern end of the beach, a bar was thrown across the valley, and 

 the beach slowly developed as the land continued to sink. The mouth 

 of the harbour was subsequently changed to the present outlet. 



Allnviuin. — Owing to the late elevation oi the land, the slopes of the 

 streams have not been reduced sufficiently to allow the deposition of 

 much alluvium along their courses. However, at the mouths of many 

 of the rivers, especially along the southwestern end of the island, there 

 are extensive marshes. Indeed, from their broad character, a late sub- 

 sidence seems to have occurred, if not in progress at present. The sink- 

 ing of Port Royal (at the end of the Kingston Palisades) in 1697, from 

 earthquake action cannot be taken as evidence of changes of level of 

 the coast line. 



A Review of Ej'osion Features since the Miocene Period. — The 

 features of denudation have formed prominent diagnostics in the pres- 

 ent researches, and consequently had to be separated and partly con- 

 sidered in several connections. In these erosion features, the records of 

 the history of the land are as clearly told, as in the fossils is the history 

 of the sea. Owing to changing conditions from terrestrial to marine, 

 and back again, both departments of geology have to be considered, 

 and each makes the other study the more valuable. The Mio-Pliocene 

 denudation was enormous, but it was effected with the land near the 

 base level of erosion. This condition need not imply that the land was 

 actually low, but the sea may have been much farther from the modern 

 plateau than now, as is suggested from the submarine banks, only in the 

 elevation of the land Jamaica may have been abnormally lifted above 

 the now submerged plateau ; and the seaward margins, from which 

 even the " White Limestones " had been mostly denuded, were de- 

 pressed. Since the early Miocene period, the "White Limestones" 

 themselves have been raised 3,000 feet. The Mio-Pliocene period was 

 one of erosion affecting the island beyond its present margins ; and 

 this long period of denudation was ended by the Layton submer- 

 gence. The post-Layton degradation, (that is the early Pleistocene), 

 was also of considerable duration, and represented very great eleva- 

 tion with the formation of deep valleys, but the country was not 

 ground down to the base level of denudation as during the long 

 Mio-Pliocene elevation. The later, or post-Liguanea, erosion has been 



