S. F. Peckham—The Pitch Lake of Trinidad. 457 



misleading. With the term volcanic is usually associated sti'eams 

 of melted lava, scoria, and pumice. The masses of porcellanite and 

 jasper mentioned by all observers as found in the neighbourhood of 

 the lake, do not require for their origin any " subterranean fires." It 

 only requires that hot water, holding silica in solution under high 

 pressure, shall percolate a bed of clay. The distillation of beds of 

 lignite requires nothing more. In one case the product is red or yellow- 

 jasper, in the other a deposit of bitumen. The less the pressure the 

 more dense will be the bitumen. Water will inevitably bring the 

 bitumen to the surface, unless it is held down by impervious strata. 

 If the water, accompanied by bitumen, encountered in its upward 

 passage such strata as have been described by Mr. Guppy, a mud 

 volcano yielding bitumen would be the inevitable result. It appears 

 to me that all of these conditions are present in and about the pitch 

 lake. They are exactly the conditions that have produced enormous 

 tar springs and asphalt beds in California, excepting that there the 

 strata necessary to produce mud volcanoes are wanting, but the 

 porcellanites, the hot springs, the sulphur springs, and the bitumen, 

 are all there, and in some localities on a scale that vies with Trinidad. 



I looked in vain for specimens of wood in process of trans- 

 formation into asphalt, I enquired of many intelligent men, and 

 others connected with mining the pitch, if they had ever seen such 

 specimens ; they invariably answered " no." Two or three remarked 

 that the wood never decayed in the pitch, that it came out as it 

 went in. One man replied that " if it went in rotten it came out 

 rotten." I saw in several excavations along the tramway masses 

 of vegetable matter that appeared to have been converted into 

 humus, and was told by the workmen that in time these masses 

 would become incorporated with the pitch. Such masses account for 

 the organic matter in solution in the lake water, and also for the 

 amorphous organic matter not bitumen, observed by Mr. Richardson. 



The Concessionaires of the lake have recently put in operation 

 a tramway and pier by which the pitch can be very rapidly and 

 easily removed from the lake to vessels lying at the pier. The 

 tramway forms a loop, which in a general way may be said to pass 

 just outside the circle of islets. (See map.) In building the tramway 

 much of the vegetation on these islets has been desti'oyed. The 

 laying of the tramway presented some peculiar engineering diffi- 

 culties, that have been fully overcome. The islands float on the 

 pitch, and I believe that they represent portions of the edge of 

 the crater broken off" during violent irruptions, and placed in and 

 maintained in their relative positions through their relations to the 

 various centres of ebullition into which the surface of the lake is 

 divided. These islets, which largely consist of vegetable matter, 

 float, while logs of wood and palm-tree ties sink in the pitch; it 

 therefore occurred to Mr. Freeman, the engineer in charge of the 

 work, to support his tramway on palm leaves, of which many 

 specimens are twenty-five feet in length. This expedient has proved 

 a complete success, not only upon the summits of the " areola," but 

 in crossing the crevices that separate them. The tramway furnishes 



