1904-5. ] THE GROWTH OF TRINIDAD. 139 
This phase of the development of the island is indicated in Fig. 2. 
How long as measured in years was the duration of these events, namely 
1° the deposition under water of the rocks of the Caribean formation, 
and 2° their elevation to form the Parian Range, it is impossible in 
the present state of our knowledge to conjecture, but we may assume 
that it was a period measured by hundreds of thousands of years. 
The assumption that after the elevation of the Caribean formation 
into the Parian Range it attained the height of more than five thousand 
feet above the sea is based firstly upon the fact that the series in Venezuela 
attains the height of nine thousand feet; and secondly, that since the 
elevation of that formation there have been extensive movements of 
depression which have greatly reduced the height attained by the Caribean 
formation in the Island of Trinidad. The evidence for this will be found 
in the sunken valleys and other geological phenomena which I will refer 
to in due course. 
The Government Geologists (Messrs. Wall & Sawkins, the value of 
whose work becomes more obvious every day) estimated the thickness of 
these rocks (which they styled the ‘‘Caribean Group’’) at 10,000 to 12,000 
feet. For my part I am inclined to think that here as in other parts of 
the island many strata shown as separate deposits are in reality, mere con- 
tinuations one of another, thrown up or down by dislocations. But on 
the other hand the estimated thickness may not be less than that stated 
because in the first place great portions of the strata have been removed 
by denudation; and secondly, there are beds unseen which lie beneath 
those exposed to view. 
As regards the composition of the rocks, I could not improve upon the 
description given in the Geological Report, (page 13). Clayslates, mica- 
ceous and talcose schists with quartzites, and crystalline and compact lime- 
stones, may be said to be generally characteristic of the formation. 
The compact limestones which in some places abut against the newest 
beds of the Caribean formation, are considerably later in date than that 
formation, and may possibly be Devonian or Carboniferous, while the 
Caribean Formation itself we have conjectured to be somewhere near the 
Silurian in age. The fossils hitherto found are insufficient to enable us 
to speak with any certainty on the point. 
The strike of the rocks is in general terms coincident with the direction 
of the main range, that is from east to west, with a slight divergence to the 
north of east, and south of west. The watershed or dividing ridge of this 
Parian Range, is within a mile or two of the Caribean Sea, and approximate- 
ly parallel to its shore, so that the valleys running to the northward are 
