S. F. Peckham—The Pitch Lake of Trinidad. 455 



Yet it must not be assumed that the cosmical agencies that 

 produced this deposit of bitumen have ceased to be active, or are 

 even simply quiescent. Abundant evidence is to be found in the 

 neighbourhood, and even within the lake itself, that such forces 

 are still active. A few miles to the south-west of the lake, at 

 Guapo, large springs of maltha or "liquid asphaltuni " are now 

 flowing, and within the boundaries of the lake near the power 

 station of the tramway, and within only a few rods of the edge of 

 the cone, I observed what the workmen called (and very properly) 

 a "blow-hole." This was a circular hole, about six inches in 

 diameter, from which bitumen, more nearly fluid than any I saw 

 elsewhere upon the island, had been ejected to the amount of 

 perhaps a barrel. It was so soft as to flow readily, of a brilliant 

 black colour, and appeared to contain little, if any, mineral matter. 

 I was told by a workman that such holes occurred quite frequently 

 and so far apart as apparently to have no connection with each other. 

 Asphalt beds occur in California that are the product of the 

 hardening of maltha, or mineral tar, which escapes over a con- 

 siderable area. Sometimes it flows continuously from a central 

 orifice, but oftener the flow through the hot summer seems to be 

 arrested by the lower, winter temperature, when the orifice through 

 which the flow took place becomes plugged. The succeeding season 

 the maltha issues along a line of less resistance and flows through 

 the summer, when it in turn becomes plugged. These plugged 

 orifices are often several rods apart for successive seasons, and 

 present the appearance of a cicatrix. I have no doubt that more 

 extended observations than I was able to give would reveal a similar 

 condition of outflow at and in the vicinity of the lake. 



I carefully studied these phenomena as likely to offer some 

 suggestion concerning the origin of the deposit. As a description 

 of the observed facts, I can add nothing to that of Mr. Manross. 

 I do not understand why Messrs. Wall and Sawkins observed 

 nothing of the sort described by him, or thought it not "very 

 obvious to what force or what influence this is attributable." These 

 "areola" are very irregular in shape. I think their form may be, 

 to some extent, determined by the weight of water pressing against 

 their sides. The surface of each one is slightly rounded from the 

 centre to the edge of the water; they then round off at a very 

 sharp angle, finally descending almost perpendicularly. These 

 areas consist of pitch inflated with gas to such an extent, that 

 when broken into the structure exactly resembles an over-fermented 

 cheese— hence the term " cheese-pitch." The cavities are from one 

 to three or more inches in dimensions. The gas that they contain 

 is constantly rising to the surface, where it bubbles out and bursts, 

 thus forcing the centre up, and causing a slow but irresistible move- 

 ment from the centre towards the cii'cuniference, where the pitch 

 continually rolls under exactly as Manross has described it. His 

 suggestions concerning the ebullition of the mass within the lake 

 were confirmed to the very letter. 



This action is explained in this wise : Mr. Kichardson's analysis 



