In meandering along the Texan bank of the river as a land surveyor, from the New Mexican line to a point below Fort Quitman, in 1858, 1859, and 1860, I observed that the deposit was from one-half inch to 3 inches annually, that during the floods the bed of the river was constantly changing by erosion and deposit, and that in regular cycles it shifted from one of its firm rocky or clay banks to the other, as the deposits had raised the side of the valley through which it then flowed above the level of the opposite side. Generally this change took place slowly, by erosion and deposit of matter entirely in suspension; but frequently hundreds of acres would be passed in a single day by a cut-off in a bend of one channel, and sometimes the bed would suddenly change from one firm bank to the other, a distance of perhaps 20 miles in length by 6 in width. For instance, when surveying "El Canutillo," a valley a short distance above El Paso, the river was moving westward, and about the middle of the valley, which was some 6 miles wide. Old Mexicans who had lived in the vicinity informed me that in 1821 the river ran close along the eastern bluff, where its bed was plainly to be seen, as was also a less plainly outlined bed along the bluffs on the opposite side, where the river flows at this date, and gives evidence of returning abruptly to the eastern bluffs again at the next greatest high tide, to its old channel along the bed of the track of the Santa Fe Railroad. In another case, more recent and extensive, in the great valley below El Paso, some 12 miles in width and 20 miles long, the river, as was plainly evident at the time I was surveying the land, had made a sudden change from the bluffs on the eastern or Texan side to the western or Mexican side of the valley. Mexicans who had been residents continuously in that vicinity informed me that this change took place in 1842. Again, in 1884, in this vicinity, the river swept suddenly from the Mexican side, crossed the Southern Pacific Railroad, and destroyed both track and bed for a distance of 15 miles, stopping traffic for a period of three months and causing the removal of the road to hills above the valley.