Page:Popular Science Monthly Volume 81.djvu/177

From Wikisource
Jump to navigation Jump to search
This page has been proofread, but needs to be validated.
171
TRINIDAD AND BERMUDEZ ASPHALTS

PSM V81 D177 Bermudez pitch lake in venezuela.png

Photo. W. H. Rau, Philadelphia.

Bermudez Pitch Lake, Venezuela.
 

while the deepest part of the soft maltha is only 9 feet and the average of pitch below the soil and coke only 4 feet. At points there is not more that 2 feet of pitch, and in the morichales or palm groves it is often 5 feet below the surface. At several points scattered over the surface are areas of soft pitch, or pitch that is just exuding from springs. The largest area is about 7 acres in extent and of irregular shape. This has little or no vegetation upon it, and from the constant evolution of fresh pitch is somewhat raised above the level of the rest of the deposit. This soft asphalt has become hardened at the edges, but when exposed to the sun is too soft to walk upon. The material is of the nature of a maltha and it is evidently the source of all the asphalt in the lake, from these exudations the pitch having spread in every direction, so that no great depth of pitch is found even at this point.

A careful examination of the surroundings shows that in one respect there is a resemblance between the point of evolution of the soft pitch at the Bermudez and at the Trinidad lakes. Gas is given off in considerable quantities at both places, and in both cases consists, partly, at least, of hydrogen sulphide.

The consistency of the soft pitch at the center of the Bermudez lake is much thinner than that of the Trinidad lake. It will run like a heavy tar and does not evolve gas in the same rapid way or harden as quickly after collection. It therefore does not retain the gas which is generated in it, nor does the deposit as a whole do so to the same extent as the Trinidad pitch.