364 PROF. SPENCER ON THE GEOLOGICAL AND [ Aug. 1902, 
a way as to suggest the recent elevation of the district, which view 
is supported by the occurrence of a neighbouring cataract 340 feet 
in height. These and other similar observations show that the old 
Miocene-Pliocene land-surfaces continued long in Trinidad, as in 
the West Indian Islands, and that they were subsequently covered 
by a thin mantle of mechanical deposits, which further observation 
would probably show to belong to two series, as on the North 
American continent. 
X. SuMMARY AND Conclusions. 
Except the crystalline schists of Trinidad, the oldest formations in 
both that island and Barbados are shore-accumulations, which have 
been referred to the Eocene Period, though possibly somewhat 
older. Then succeeds in both islands the Oceanic Series, deposited 
in oceanic abysses. at perhaps depths of 2 miles or more. This 
great subsidence was followed by an elevation of the region, so 
that the subsequent denudation not only moulded the surface of the 
Oceanic Deposits, but in places cut through them; and upon this 
foundation the White-Limestone Series, or the Antigua Formation, 
was accumulated in comparatively shallow water. This wide- 
spread formation has been found to belong to the Oligocene Period. 
It was then elevated, so that throughout the long Miocene-Pliocene 
Period it formed the surface of the land—which stood at a high 
altitude at first, and later, at a lower one—when the broad undu- 
lating topographic features of the Antillean Plateau, now in part 
submerged to over 7000 feet, were produced. Then followed a sub- 
sidence which carried the land to 100 feet below the present level, 
when the Ragged-Point Series was accumulated unconformably upon 
the older formations, about the close of the Pliocene Period. 
Upon the subsequent emergence, the land rose to such a 
height as to favour rapid and extensive denudation, so that the 
Ragged-Point mantle now remains only in protected places. The 
Bath-Reef Series (occurring at a height of 165 feet or more) shows 
another very great subsidence, subsequent to a post-Ragged-Point 
elevation, with the accumulation of fossils belonging to living 
species. Much of the great denudation of the Ragged-Point Series 
was subsequent to the Bath episode, for this series has also 
been dissected and very largely removed, so as to expose the 
lower mechanical formation. The great topographic features of 
this epoch are to be seen in the deep river-like valleys and cirques, 
such as now indent the margins of the drowned plateau ; these, while 
scarcely observable in the scanty soundings on the steep submarine 
slopes of Barbados, may be traced to depths of 6000 or 7000 
feet near St. Lucia and St. Vincent, and to a less degree at the 
mouth of the Gulf of Paria. Possibly the valley shown in the 
deep sounding of 8958 feet, west of Barbados, may have been 
produced at this time (see map, Pl. X). 
The early Pleistocene elevation was succeeded by a depression of 
the region, so that Barbados sank to over 1000 feet lower than now, 
and formed only a little low islet, like Sombrero, lying alone far 
out in the ocean. During this episode of subsidence, some of the 
