other-a feature in which the smaller apparent differences BOOK are lost. LXXV. Continent. This correspondence and continuity of the two great) On the islands of the globe, already leads us to reject the idea of term New the more recent origin of America-an opinion which one is almost ashamed of being under the necessity of refuting, since it is contrary to the established laws of hydrostatics. Yet, how many opinions are maintained in geology, which are contrary to the laws of physics! We must, therefore, repeat, that the level of the sea being necessarily, within a few feet, every where the same, no considerable tract of country can either be more ancient, or, especi ally, more recent than the rest. The expression, New Continent, ought merely, therefore, to recall the chronological order of our knowledge. the coun try. The general level of America in reality presents a re- Level of markable difference from that of the old continent. This difference does not consist in the greater height of its mountains; for, if the Cordilleras of Peru rise, by some of their summits, twenty thousand feet, we are now almost certain that the mountains of Thibet attain an equal, and perhaps a still greater elevation. But the plateaus, which support these mountains, are separated in America from the low plains by an extremely short and rapid declivity. Thus, the region of the Cordilleras, and that Elevated of the table land of Mexico-aerial, temperate, and sa- regions. lubrious tracts of country-come in immediate contact with the plains watered by the Mississippi, the Amazon, and the Parana. Even these plains, whatever may be their nature-whether they are covered with tall and waving plants, as the savannahs of the Missouri; or offer to Savanthe view, like the Llanos of the Caraccas, a surface, at one nahs, Lanos, and time burnt up with the sun, and at another refreshed by Pampas. tropical rains, and clothed with superb grasses; or, in fine, similar to the Pampas, and to the Campos Parexis, A. de Humboldt, Berliner Monat-Schrift, t. XV. p. 191. Smith Barton's Natural History of Pennsylvania, t. I. p. 4. and low BOOK they oppose to the fury of the winds their hills of moving LXXV. sand, intermingled with stagnant ponds, and covered with saline plants;-all of them preserve so very low a level as to be rarely interrupted by rising ground: for the ridge of the Apalachian or Alleghany mountains, in North America, and that of the Cordilleras of Brazil, in South America, are only connected with the great central chain of the Cordilleras by plateaus of little elevation, or by mere acclivities, and inconsiderable eminences.* From this vast extent of the American plains, results the immense length of the rivers which water that part of the globe. Of this, the following table may convey an idea: LENGTH AND COURSE OF AMERICAN RIVERS. Basin of the Gulf of Mexico, (subordinate to the Atlantic.) . Missouri, with the lower Mississippi 575 980 See The Levels of the Continents,' pl. 4. of vol. I. of this summary; or, the Levels of Mexico, in the Atlas of M. de Humboldt. on the beds Owing to this continuation of the same level, the re- Remarks spective beds of the rivers are no where less distant from of its riveach other; for some are divided by mere ridges, and fre- ers. quently even these are deficient. Accordingly, many rivers mingle at the early part of their course those waters which are destined for different estuaries. Thus, the Orinoco, and the Rio Negro, a tributary to the Amazon, communicate by the Cassiquiary; and a similar branch unites the Beni and the Madeira. It appears certain that, in the rainy season, a boat might pass from the tributary streams of the Paraguay into those of the Amazon, which wind along the elevated plain called Campos Paraxis. In North America, the same circumstance has Great produced an infinite number of lakes. The Slave Lake, of lakes. the Assiniboin, and the Winnipeg, are surrounded by a hundred others, that are likewise of a very considerable size, and by many thousand lesser ones, which in general number BOOK are bordered by a ridge of rocks, like those of Finland. LXXV. The country becomes less covered with water as we ad Two general clim ates. vance towards the south. Still, nevertheless, Lake Superior, Michigan, Huron, Erie, and Ontario, in Canada, form almost a sea of fresh water, whose superfluous waters precipitate themselves by the river Saint Lawrence, into the Atlantic Ocean. South America, under a more burning sky, sees its lakes rise and disappear with the rainy season. The Xarayes, and the Fbera, are of the number of these more or less periodical lakes; amongst which the Parima, better known, will one day take its place. From this general division of America into lofty mountainous plateaus, and very low plains, there results a contrast between two climates, which, although of an extremely different nature, are in almost immediate proximity. Peru, the valley of Quito, and the city of Mexico, though situated between the tropics, owe to their elevation the genial temperature of spring. They behold even the Paramos, or mountain ridges, covered with snow, which continues upon some of the summits almost the whole year, while, at the distance of a few leagues, an intense and often sickly degree of heat suffocates the inhabitants of the ports of Vera Cruz or of Guayaquil. These two climates produce each a different system of vegetation. The flora of the torrid zone forms a border to the fields and groves of Europe. Such a remarkable proximity as this, cannot fail of frequently occasioning sudden changes, by the displacement of these two masses of air, so differently constituted,—a general inconvenience, experienced over the whole of America. Every where, however, this continent is exposed to an inferior degree of heat. Its elevation alone explains this fact, as far Causes of as regards the mountainous region; but why, it may be asked, does it extend to low tracts of country? To this an able observer makes the following reply: "The trifling breadth of this continent; its elongation towards the icy poles; the ocean, whose unbroken surface is swept the low temperature. LXXV. by the trade winds; the currents of extremely cold wa- BOOK ter which flow from the Straits of Magellan to Peru; the numerous chains of mountains abounding in the sources of rivers, whose summits, covered with snow, rise far above the region of the clouds; the great number of immense rivers that, after innumerable curves, always tend even to the most distant shores; deserts, but not of sand, and consequently, less susceptible of being impregnated with heat; impenetrable forests, that spread over the plains of the equator, covered with rivers, and which, in those parts of the country that are the farthest distant from mountains and from the ocean, give rise to enormous masses of water, which are either attracted by them, or are formed during the act of vegetation. All these causes produce, in the lower parts of America, a climate which, from its coolness and humidity, is singularly contrasted with that of Africa. To these causes alone, must we ascribe that abundant vegetation, so vigorous and so rich in juices, and that thick and umbrageous foliage, which constitute the characteristic features of the new continent."* Assuming this explanation as sufficient for South America and Mexico, we shall add, with regard to North America, that it scarcely extends any distance into the torrid zone; but, on the contrary, as we shall see in the succeeding book, stretches, in all probability, very far into the frigid zone, and, unless the revived hope of a North-West passage be confirmed, may, perhaps, reach and surround the pole itself. Accordingly, the column of frozen air attached to this continent, is no where counterbalanced by a column of equatorial air. From this results an extension of the polar climate to the very confines of the tropics; and hence winter and summer struggle for the ascendency, and the seasons change with astonishing rapidity. From all this, however, New Albion and New California are happily exempt; for, being placed beyond the reach A. de Humboldt, Tableaux de la Nature, t. I. p. 23. Trad. de M. Eyries. |