Judging From The Aspect Of The Soil We Might Have Believed Ourselves To Be In The Temperate Zone And Even

Still farther northward but that a few scattered palms, and at nightfall the fine constellations of the southern sky (the

Centaur, Canopus, and the innumerable nebulae with which the Ship is resplendent), reminded us that we were only eight degrees distant from the equator.

A phenomenon which fixed the attention of De Luc and which in these latter years has furnished a subject of speculation to geologists, occupied us much during our journey across the Llanos. I allude not to those blocks of primitive rock which occur, as in the Jura, on the slope of limestone mountains, but to those enormous blocks of granite and syenite which, in limits very distinctly marked by nature, are found scattered on the north of Holland, Germany and the countries of the Baltic. It seems to be now proved that, distributed as in radii, they came at the time of the ancient revolutions of our globe from the Scandinavian peninsula southward; and that they did not primitively belong to the granitic chains of the Harz and Erzgeberg, which they approach without, however, reaching their foot.* (* Leopold von Buch, Voyage en Norwege volume 1 page 30.) I was surprised at not seeing one of these blocks in the Llanos of Venezuela, though these immense plains are bounded on the south by the Sierra Parima, a group of mountains entirely granitic and exhibiting in its denticulated and often columnar peaks traces of the most violent destruction. Northward the granitic chain of the Silla de Caracas and Porto Cabello are separated from the Llanos by a screen of mountains that are schistose between Villa de Cura and Parapara, and calcareous between the Bergantin and Caripe. I was no less struck by this absence of blocks on the banks of the Amazon. La Condamine affirms that from the Pongo de Manseriche to the Strait of Pauxis not the smallest stone is to be found. Now the basin of the Rio Negro and of the Amazon is also a Llano, a plain like those of Venezuela and Buenos Ayres. The difference consists only in the state of vegetation. The two Llanos situated at the northern and southern extremities of South America are covered with gramina; they are treeless savannahs; but the intermediate Llano, that of the Amazon, exposed to almost continual equatorial rains, is a thick forest. I do not remember having heard that the Pampas of Buenos Ayres or the savannahs of the Missouri* and New Mexico contain granitic blocks. (* Are there any isolated blocks in North America northward of the great lakes?) The absence of this phenomenon appears general in the New World as it probably also is in Sahara, in Africa; for we must not confound the rocky masses that pierce the soil in the midst of the desert, and of which travellers often make mention, with mere scattered fragments. These facts seem to prove that the blocks of Scandinavian granite which cover the sandy countries on the south of the Baltic, and those of Westphalia and Holland, must be traced to some local revolution.

Enter page number Go  Previous Next
Page 80 of 332
Words from 41615 to 42143 of 174507