Its Edges, A Little Translucid, Give It Some Resemblance To The Hornstone, So Common In Secondary Limestones.* (* In Switzerland, The

Hornstone passing into common jasper is found in kidney-stones, and in layers both in the Alpine and Jura limestone,

Especially in the former.) It is remarkable that we find the schistose jasper which in Europe characterizes the transition rocks,* (The transition-limestone and schist.) in a limestone having great analogy with that of Jura. In the study of formations, which is the great end of geognosy, the knowledge acquired in the old and new worlds should be made to furnish reciprocal aid to each other. It appears that these black strata are found also in the calcareous mountains of the island of Boracha.* (* We saw some of it as ballast, in a fishing boat at Punta Araya. Its fragments might have been mistaken for basalt.) Another jasper, that known by the name of the Egyptian pebble, was found by M. Bonpland near the Indian village of Curacatiche or Curacaguitiche, fifteen leagues south of the Morro of Barcelona, when, on our return from the Orinoco, we crossed the llanos, and approached the mountains on the coast. This stone presented yellowish concentric lines and bands, on a reddish brown ground. It appeared to me that the round pieces of Egyptian jasper belonged also to the Barcelona limestone. Yet, according to M. Cordier, the fine pebbles of Suez owe their origin to a breccia formation, or siliceous agglomerate.

At the moment of our setting sail, on the 19th of November, at noon, I took some altitudes of the moon, to determine the longitude of the Morro. The difference of meridian between Cumana and the town of Barcelona, where I made a great number of astronomical observations in 1800, is 34 minutes 48 seconds. I found the dip of the needle 42.20 degrees: the intensity of the forces was equal to 224 oscillations.

From the Morro of Barcelona to Cape Codera, the land becomes low, as it recedes southward; and the soundings extend to the distance of three miles. Beyond this we find the bottom at forty-five or fifty fathoms. The temperature of the sea at its surface was 25.9 degrees; but when we were passing through the narrow channel which separates the two Piritu Islands, in three fathoms water, the thermometer was only 24.5 degrees. The difference would perhaps be greater, if the current, which runs rapidly westward, stirred up deeper water; and if, in a pass of such small width, the land did not contribute to raise the temperature of the sea. The Piritu Islands resemble those shoals which become visible when the tide falls. They do not rise more than eight or nine inches above the mean height of the sea. Their surface is smooth, and covered with grass. We might have thought we were gazing on some of our own northern meadows. The disk of the setting sun appeared like a globe of fire suspended over the savannah; and its last rays, as they swept the earth, illumined the grass, which was at the same time agitated by the evening breeze.

Enter page number Go  Previous Next
Page 302 of 407
Words from 156702 to 157227 of 211363