321 
Guppy Reprint 
173 
sediment underlying the tenacious clay of the bars.” 
The material of this mud-lump (which ma}^ be called the 
‘‘Despatch Reef Mudlump”), for samples of which I am indebted 
to Mr. John Wilson, is of ver}- various degrees of consistenc}^ 
hardness and fineness of component parts. It contains a large 
quantity of sulphuret of iron and a few pieces of lignite. Beds 
of clastic matter vary ing from small pebbles to find sand indicate 
estuarine beaches and these are derived from the degradation of 
tertiary’ and cretaceous rocks, but there is nothing to indicate the 
Page 2g 
existence of deep-sea deposits. In the softer material, a ver}- im- 
pure gra}’ ooze or cla}', I have found two or three Foraminifera, 
for example, Cyclamina cancelata and Amodiscus incertus, but 
their condition shows that the}’ have been derived from older beds 
and they are not characteristic of deep water. 
The sunken valleys of the Bocas Region are worthy of notice 
and they show how much the interest of the traveller in what he 
sees would be increased b.v a slight acquaintance with geology. 
We have in this region almost every kind of sunken or submerged 
valle}’. First we have the submerged valle}’ which has been en- 
larged to several times its original width by the rapid tidal cur- 
rents running through it. Such are the channels between the 
Gulf of Paria and the Caribean Sea called the Bocas. Next we 
have the valley which has been partly submerged, but which has 
not been enlarged to any noticeable extent, because no current 
runs through it. As an example of this we may take Scotland 
Bay. On the opposite side of the gulf, that is on the Venezuelan 
coast, there are several examples of this kind. Teteron is an in- 
intermediate case between the submerged valley and that which 
is parti}- filled up. The valley of Chaguaramas and more notably 
those of Cuesa and Diego-martin are examples of sunken valle}-s 
of w'hich the lower parts have been filled up. 
These phenomena are alluded to in several of my papers (See 
particularly ‘‘Growth of Trinidad” Trans. Canadian Imst. 1904-5. 
p. 141, &c. Ibid. 1908-9, p. 379.) 
