S. F. Peckham—Pitch Lake of Trinidad. 39 
dary of the Carribean continent and was a barrier through 
which no large river found its way. The ‘Parian Range’ 
may be regarded as one of those ‘stable areas’ which has 
never been submerged since Paleozoic times.” 
“To the westward the Cretaceo-Eocene sea probably ex- 
tended as far as the present low-lying alluvial plains of Vene- 
mela. In this direction it was no doubt bounded by the high 
lands now forming the Pico de Cumanacoa and the Cerro del 
Bergantin, ranges at present twice as high as any in Trinidad. 
Its southern extension went presumably near to the granitic 
and gneissic ranges and plateaux of Guiana.” 
“ After the close of the Miocene period there was probably 
in the region south of the ‘Parian Range’ a slow and grad- 
ual upheaval which brought the oceanic deposits above the 
level of the sea, during which process they suffered great 
denudation. The Gulf of Paria was then land, and Trinidad 
was then united to the mainland. At that time the. river 
Guarapiche probably flowed across Trinidad from Venezuela, 
while the Orinoco continued to pour its waters into the ocean 
at some distance southward. The disruption of the ‘ Parian 
Range’ and the formation of the Bocas and the Gulf of Paria 
followed. ‘There are paleontological reasons for believing that 
this submergence did not take place until a late geological 
epoch.” 
From this conclusion it is manifest that the Miocene period 
was one of frequent alternation of elevation and submergence, 
during which there were long periods when the different mem- 
bers of the formation were covered with tropical swamps 
having luxuriant vegetation, that are now represented by the 
great swamp at the east end of the island. The buried vege ta- 
tion of these swamps has been converted into coal through 
Pliocene and recent times which has been distilled at low 
temperatures, probably initiated by fermentation within the 
mass of the coal itself, assisted by the water of thermal 
springs. 
Messrs. Wall and Sawkins discuss at length the phenomena 
peculiar to the lake and disagree with previous observers to 
such an extent that, after a careful examination of their paper 
I am forced to the conclusion that their study of the subject 
was extremely superficial. In illustration: they say of the 
“areas,” “the surface is frequently marked with ridges, espec- 
ially near the edges; these are due to the constant expansion 
and contraction which is supposed to occur.” A most singular 
explanation, resting on swpposed phenomena that were neither 
observed nor proved theoretically. Although they quote Bis- 
choff,* it is only to prove a possible origin for the asphaltum 
* Bischoff, Chem. and Phys. Geol. (Cav. Soc. Ed.), i, 288, 290, 291. 
