34 Geootapbtcal IRotes on 



Whirlpools, and a high cascade. The Panuco River rises north of the 

 Valley of Mexico. Under the names of Tula and Montezuma it de- 

 scribes a vast semicircular bend towards the west across the Hidalgo- 

 uplands and collects the waters of the Huasteca of Veracruz and Ta- 

 maulipas, beyond which it is joined by the various streams flowing: 

 from Queretaro, and finally empties into the Gulf of Mexico at the 

 port of Tampico. The Tampico bar, improved by jetties, is now the 

 best harbor on our Gulf coast. The Rio Lerma or Santiago, the 

 Tololotlan of the Indians, is also a considerable stream. By the 

 riverain populations it is, in fact, known as the Rio Grande, while 

 the inhabitants of Michoacan call it also Cuitzeo, from the large 

 lake situated in their State. It rises in the State of Mexico in 

 the very centre of the Anahuac plateau, and its farthest sources r 

 issuing from underground galleries, descend from the Nevado de 

 Toluca down to the twin lake of Lerma, the remains of an inland 

 sea which formerly filled the Upper Toluca valley north of the Ne- 

 vado volcano. At its issue from the lake, or rather marshy lagoon, 

 the Lerma stands at the great altitude of 8600 feet, and during its 

 winding northwesterly course across the plateau, the incline is very 

 slight. In this upland region it is swollen by several affluents, some of 

 which, like the main stream itself, flow from lakes dotted over the 

 table-land. After completing half of its course at La Barca, the Ler- 

 ma is still 5600 feet above sea-level. Here, some 280 miles from its 

 source, it enters the large Lake Chapala, near its eastern extremity ; 

 but about twelve miles below the entrance it again emerges through 

 a fissure on the north side of the lake, and still continues to flow- 

 throughout its lower course in the same northwesterly direction. 



The Grijalva and Usumacinta rivers, rising in the State of Chiapas,, 

 after being joined by many others, some of them coming from Guate- 

 mala, empty into the Gulf of Mexico by one of its mouths at the city 

 of Frontera in the State of Tabasco. The Papaloapam River rises in 

 the State of Oaxaca, passes through the State of Veracruz, and emp- 

 ties into the Gulf of Mexico at the town of Alvarado, a few miles south 

 of Veracruz. 



The rains increase considerably the amount of water in the rivers,, 

 but as their duration is not very long this soon subsides. When the 

 streams rise near the sea, as is the case on the coast of Chiapas on the 

 Pacific, they become so swollen immediately after the rains that it is 

 impossible to ford them, and as there are no bridges, it is necessary to 

 wait until early the next day when the freshet has subsided. 



Springs are rare, and some of the rivers run in deep mountain beds, 

 without receiving smaller tributaries, while the rapid evaporation on a 

 light soil, covering porous rocks, leaves the surface dry and hot and 

 unable to support much vegetation beyond the cactus and low grasses. 



