The river systems of Mexico and Central America flow into the two bounding oceans or into lakes which have no outlets. Several closed basins occur on the Mexican table-land. The Rio Nazas and the Rio Nieves flow into salt marshes in the northern state of Coahuila. But the most important interior basin is the Valley of Mexico. In this mountain enclosed valley, whose general level is 7,500 feet above the sea, there are five lakes which in order from north to south are named Tzompanco, Xaltocan, Texcoco, Xochimilco, and Chalco. The last two contain fresh water, since they drain into Lake Texcoco, but the rest are more or less brackish. Lake Texcoco is by far the largest, although its area has been greatly reduced by natural and artificial causes since the coming of the Spaniards.
The largest river of Mexico is the Rio Lerma which takes the name Rio de Santiago during its deep and tortuous passage from Lake Chapala to the Pacific. Farther to the south is the Rio de las Balsas which likewise flows into the western ocean. The name means “River of the Rafts” and is given because of a peculiar floating apparatus made of gourds tied to a wooden framework that is used on this stream. Flowing into the Gulf of Mexico are several large streams, among which may be mentioned the Panuco, Papaloapan, Grijalva, and Usumacinta. The last is by far the greatest in volume of water, and with its maze of tributaries drains a large area of swamp and jungle in which are buried some of the most wonderful ruined cities of the New World.
In the northern part of Yucatan there are no rivers on the surface on account of the porous limestone. Instead there are great natural wells called cenotes where the roofs of subterranean rivers have fallen in. Many of the ancient cities were built near such natural wells.
Passing to the south the most important river of Guatemala is the Motagua, which has cut a fine valley through a region of lofty mountains. In Honduras there are several large rivers, including the Uloa, Patuca, and Segovia. The lake region of Nicaragua is drained by the San Juan River that flows into the Caribbean Sea. Nearly all the streams of Central America that flow into the Pacific are short and steep torrents. An important exception is the Lempa River that forms part of the interior boundary of Salvador.
Concerning lakes, mention has already been made of Chapala and Texcoco, the most important in Mexico. The former is about fifty miles in length. In the state of Michoacan there are a number of beautiful lakes intimately connected with the history and mythology of the Tarascan Indians. The most famous is called Patzcuaro. In southern Yucatan the shallow body of water known as Lake Peten also has a distinct historical interest. Several lakes in Guatemala are well known on account of the rare beauty of their situation. Lake Atitlan is surrounded by lofty mountains, and Lake Izabal, or Golfo Dulce, is famous for the luxuriance of the vegetation that screens its banks. Lakes Nicaragua and Managua are well known on account of their connection with the much-discussed canal projects. The Island of Ometepe in Lake Nicaragua bears an active volcano.
In regard to the geology it is only necessary to point out a few of the more important characters. The highlands which bear so many active and quiescent volcanoes naturally show great masses of eruptive rocks, some due to recent action and others much more ancient. Porous tufa is a common material for sculptures in many parts of Mexico and Central America. In other places there are great beds of softer and finer grained material also of volcanic origin. In these places, such as Copan in western Honduras and Mitla in southern Mexico, building in stone received its greatest development. The soft greenish stone of Copan seems to be a solidified mud flow permeated with volcanic ash rather than a true lava flow of melted rock. Limestones are also common and important in the economic development. In some regions there are beds of a hard, blue limestone going back to the Carboniferous epoch. This stone makes an excellent cement after burning. The Peninsula of Yucatan is a great plain of limestone of much more recent formation. Like our own Florida it was once a coral reef which was lifted above the sea by some natural agency. This limestone gets older and more solid as we approach the base of the peninsula but at best is rather porous and coarse-grained.
Fig. 3. Yucatan Deer caught in a Snare. From the Mayan Codex, Tro-Cortesianus.
The fauna and flora present great variation. In the moist lowlands the monkeys play in the tree tops and the jaguar lies in wait for its prey. Alligators and crocodiles infest the rivers and swamps. Two small species of deer and the ocellated turkey are important items in the meat supply of Yucatan, that includes also the iguana, the peccary, and various large rodents. The tapir and manatee are the largest animals of the lowlands but neither seems to have been of great significance to the natives. Bats are frequently represented in the ancient art and a bat demon appears in several myths.
