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



formation embraces much of what the Jamaican geologists call the 

 alluvium without further designation. Its principal development is on 

 the southern side of the island, as the mountains come close to the sea 

 upon the northern side, but even there it occurs at many places. It 

 has been seen at all altitudes below 600 feet, but it may not in every 

 district reach so high. The stratification of the loam is often indistinct, 

 or it may be characterized by lines of pebbles, especially in the lower 

 portion of the series. Yet, in the sections exposed by some of the 

 streams, the stratification is shown, and in the delta where the Hope 

 River leaves the mountains, it is over 100 feet thick, with a large 

 amount of the material composed of stratified gravel, often coarse, with 

 even large boulders from the mountain valley deposited along the bed 

 of the streams. The pebbles are all water-worn, and where not 

 wanting, constitute the lower part of the formation. They are in 

 places composed of both White Limestones and older rocks brought 

 down by the streams. 



The loams vary from grayish to reddish, according to the sources of 

 the materials. The redder loams are apt to contain great quantities of 

 pellets of oxides of iron. The loams are derived from the residual 

 soils, accumulated upon the decay of the White Limestones being 

 washed down to the sea. Such materials may also be commingled 

 with disintegrated shaly or sandy rocks brought from the interior by 

 the streams. Back of Kingston, (see Figure i, Plate V.), the formation 

 forms a mantle occurring up to an elevation of 550 feet on the Mono 

 estate, and somewhat higher nearer the delta where the Hope River 

 leaves the mountains. At this locality the river has cut through and 

 exposed nearly 150 feet of loams, gravels and boulders. The location 

 may be seen in Map, (Figure 4, page Z2)7)- The Liguanea plains 

 slope a hundred feet in the mile, but outside the gorge of the Hope, the 

 surface is seldom deeply channeled by the running waters. The surface 

 appears to have been originally in steps which are now generally 

 reduced to a nearly uniform grade. In St. Thomas-in-the-Vale, the 

 Liguanea gravels and loams were noticed at elevations between 300 and 

 400 feet. On the seaward side of Long Mountain, east of Kingston^ 

 the Liguanea formation rests unconformably upon the Layton series at 

 an elevation of 1 50 feet. 



Overlying the volcanic rocks and also the Layton marls, where not 

 eroded upon the seaward side of the volcanic hills of Low Layton, the 

 stratified Liguanea gravels occur. The formation was seen to an 

 elevation of nearly 450 feet. This is illustrated in Figure 2, Plate V. 



