CHAPTER I. Geological and Geographical Structure of Mexico—Extent.

stream is formed of the river Rafael in about 40° 15´ north, and 110° 50´ west longitude from Paris, on the western declivity of the Sierra de las Grullas, whence it takes a south-west course and receives, at the foot of the Monte de Sal Gemme, the Rio de Nuestra Señora de Dolores, which springs about 1° 30´ west of the Rafael, in the Cerro de la Plata; and, thus, receiving the accretions of a number of other streams, it courses onward until it is lost at the head of the Gulf of California. The whole length of the Colorado is estimated at about two hundred and fifty leagues. For about fifty leagues it is navigable by small sea going vessels; and, for about a hundred leagues higher, it may be traversed by large boats. The sea is said to ebb and flow between thirty-five and forty leagues beyond the mouth of this river. The sources of the Arkansas and of the Rio Grande del Norte lie very near those of the Colorado; so that the waters of the Gulf of Mexico and of the Gulf of California are nearly united by these streams across our continent.