Page:Popular Science Monthly Volume 81.djvu/27

Rh in the wards of La Brea and Guapo, in the County of St. Patrick, on the western shore of the island. They are about 28 miles in an air line from Port of Spain, the seat of government, the chief harbor and only port of entrance, and lie on the north shore of the southwestern peninsula, the point on which they are situated being apparently preserved from destruction by the sea, which is elsewhere rapidly wearing away the coast, by the bituminous deposits which exist along the shore and even some distance from it, and which from their toughness resist the action of the waves better than the soft rocks of this region. The pitch deposits are found scattered over the point, but can be divided conveniently into two classes, according to their source.

The main deposit is a body of pitch known as the pitch lake, situated at the highest part of the point. Between this and the sea, and more especially toward La Brea, are other deposits, covered more or less and mixed with soil. The pitch from these sources is classified as "lake pitch" and "land pitch."

By far the largest amount of pitch is found apparently in the pitch lake, a nearly circular area of 114.67 acres, 138-feet above sea level. From the lake the ground falls away on all sides, except, perhaps, a slight ridge to the east and southeast, in fact, it seems plain that this deposit lies in the crater of a large mud volcano which has been filled up with pitch.

In past times the pitch very probably continued to collect until it overflowed the rim of the crater, particularly toward the north, and thus perhaps became the source of some or all of the land pitch deposits now found between the lake and the sea.