Page:The American Cyclopædia (1879) Volume V.djvu/350

 346 CORDILLERA &c., large quantities of most of which are floated down the Patuca to the Atlantic coast. The temperature of the interior region is never excessive; the thermometer during the dry season from November to February seldom rises above 80 F. at noon, or falls below 55 in the morning. During the summer wet months at Jutecalpa, considerably to the east- ward of the main range and below its sum- mits, the nights are said to be always cool, and the extreme temperature of the day is below 95. Passing from Guatemala into Mexico, the mountain ranges diminish in height. At the isthmus of Tehuantepec one may pass from ocean to ocean over a summit not more than 700 ft. high. The mountains thence to the northern limits of the state spread out in a vast plateau, the height of which along its middle portion is from 6,000 to 8,000 ft. above the sea, and its greatest width near the lati- tude of the city of Mexico is about 360 m. It extends K W. at this elevation full 600 m., presenting a smooth surface, mostly unshel- tered by the growth of forest trees, though the soil is naturally fertile. Still further N. for 900 m. the plateau is traced at an elevation of from 2,000 to 3,000 ft. On either side one descends from this cool elevated region by suc- cessive steps to lower plateaus, each descent bringing the traveller into a region of warmer temperature and of more tropical produc- tions. From the tierra fria, or cold region, the first descent is to the tierra templada, or temperate tract ; the next to the tierra caliente, the low lands along the coasts, hot and un- healthy. So steep are the walls of these pla- teaus, that for a distance of 500 m. only two roads passable by carriages lead from the At- lantic coast into the interior one passing from Vera Cruz through Jalapa, and the other by Saltillo west of Monterey. On the western side the descent is hardly less precipitous, and to the south the great plateau ends abruptly near the shores of the Pacific. The climate of the plateau, though called cold, is said not to differ in its mean temperature (which is about 62 F.) from that of the central parts of Italy. There are some still more elevated tracts, as the valley of Toluca, about 8,500 ft. above the sea, where the thermometer during a great part of the day rarely rises beyond 45 F. The volcanic mountains, which are still met with along the chain as far as lat. 24 N., rise from the great plateau in stupendous masses, and penetrate with their lofty peaks the limits of perpetual snow. Their range is not, as in the more southern states, near to and parallel with the Pacific coast, but a line of them ap- pears to cross that of the great mountain chain in an E. and W. direction, passing about 16 m. 8. of the city of Mexico. The most western of them, Colima, stands alone upon the plain of the same name, situated between the pla- teau and the Pacific. Its height is about 12,- 000 ft. Smoke and ashes are frequently thrown from its crater, and an eruption began in 1869 in which vast quantities of pumice stone were ejected. Jorullo, upon the western slope of the plateau, 70 m. from the Pacific, is described by Humboldt as suddenly appearing above the surface in the night of Sept. 28 and 29, 1759, after a succession of earthquakes, accompanied by constant subterranean noises, which had continued for about three months. A tract covering several square miles rose above the plain to the height of 524 ft. Flames burst forth from all parts of this area, and burning rocks were thrown with vast clouds of ashes into the air, the softened surface of the earth rising and falling like the waves of the sea. Rivers of water flowing into the chasms caused eruptions of mud to issue from thousands of little cones that appeared upon the surface. In the midst six mountain masses were suddenly formed along a chasm ranging from N. N". E. to S. S. W. The principal one of them is the great volcano of Jorullo. Its height above the sea is 4,265 ft. ; that of the plain upon which it stands is 2,890 ft. Its great eruptions con- tinued till the month of February, 1760 ; sub- sequently they became less frequent. A wall of basalt forms the boundary of the upheaved tract, which in most places, especially on the western side, is too steep to be ascended. The celebrated valley of Mexico, nearly 7,500 ft. above the sea, and covering an area of 18 leagues in length by 12 in breadth, is en- circled by groups of mountains, among which are the famous volcanic peaks of Popocatepetl, Iztaccihuatl, and Toluca. The first rises to the height of 17,720 ft. above the sea, and 500 ft. above the termination of vegetation. Its crater is 3 m. in circumference and 1,000 ft. deep, and is in continual eruption. The sec- ond is an extinct volcano 15,705 ft. high. A chain of small volcanoes connects these with each other, and with the other volcanoes fur- ther east. The Cofre de Perote lies between Popocatepetl and the fiery Orizaba, or Citlalte- petl, "the mountain of the star," so named for the fires that ever issue from its snow-enveloped summit, dispelling as by the light of a brilliant constellation the darkness of the night through the surrounding country. Orizaba, as mea- sured by Ferrer in 1796, is 17,879 ft. high ; but later calculations by Humboldt and others re- duce these figures somewhat. It is generally thought that Popocatepetl is the higher of the two, and consequently the highest peak in Mexico. Below the plateau, in the region of low hills near the gulf of Mexico, is Tuxtla, the last of the volcanoes upon this line, a few miles west of Vera Cruz. It was in operation in 1793, when the ashes thrown from its crater were carried as far as Perote, a distance of 57 leagues. The great Mexican plateau, though a considerable portion of it is as level apparently as the ocean itself, is cleft by fissures called barrancas, two or three miles in length, and often. 1,000 ft. deep. A brook or small river flows at the bottom, the banks of which are I the precipitous and rugged walls of the chasm.