LOWER RIO BRAVO, 



71 



a distance, measured by the sinuosities of the river^ of 567 miles ; and with this in view, 

 the assistants in charge of the lineal siirvejs have heen directed to make special notes of 

 the obstructions in the river. The large maps designating the boundary, and deposited 

 in the Department of the Interior^ will form the basis upon which estimates for this 

 purpose can be made, but they are too voluminous to accompany this printed report. The 

 ideas now suggested are from the notes of assistant Arthur Schott, who was charged with the 

 lineal surveys of the river from Devil's river to Ringgold Barracks^ and from my own obser- 

 vations. 



The navigation of the river between Edinburgh and Roma is not free from obstructions. 



m 



may 



Between Roma and 



Bellville the obstructions are principally occasioned by Islands 15, 16, 17, and 20, dividing the 

 channel of the river ; and the navigation may be improved in the same way by damming all 

 the channels but one^ and dredging the bottom of the one left open. It is above Bellville that 

 obstructions become of rocky character y. difficult to remove, such as are to be found at Islands 

 25, 30, 31, 33, 35, 39 ; and above Loredo, at the Heron islands, Las Islitas^ Cazneau island, 

 and Chess-Board island. 



The worst of these are Islands 25, 30, and the Islitas ; 25 is sometimes called Major 

 !5rown's island, from the circumstance of the steamer Major Brown being detained there a 

 whole season waiting for a rise of water ; No. 30 is a couple of small islands, at the foot of 

 which the channel is only eleven or twelve feet wide. Of the three last-named obstructions, 

 the Islitas is the most formidable. Here, in fact, there is no channel, and the rocky islands 

 obstructing the passage of the water can only be passed at high water from June to September. 



Other obstructions besides islands are caused by numerous reefs and spurs of rock. Just 

 above Bellville there is a formidable obstruction of this kind, marked by the wreck of the 

 steamer '^Exchange;'' this obstruction is formed by two reefs running in from the opposite 

 sides, and overreaching each other, thus leaving but a crooked channel, through which the 

 river passes at the rate of five miles per hour. A similar obstacle occurs about fifteen miles 

 below Eagle Pass. 



Other reefs occur running entirely across the river, and are disposed in steps, one above the 

 other. In seasons of excessive dryness they are bare of water. Of such character are the 

 obstructions noted in the field-notes of Mr. Schott as 'Uhe snares," '^the meshes,'' ^*the 

 stone turtles,'' and the ^^ Devil's pen," all situated between the Islitas and Eagle Pass. 



In most cases the rocks forming the obstructions are sedimentary rocks of the upper cretaceous 

 ^S^3 ly^^g 1^ horizontal strata ; these would yield easily to the pick. How far it would be 

 prudent to resort to cutting away these natural dams, as a mode of improving the navigation, 

 which would necessarily lower the pools above, would be a subject of investigation for each 

 locality. My object in this report is only to present a general view of the character of the 

 difiiculties in the way, and to present such maps as would render unnecessary any general 

 survey of the river hereafter. 



Except where interrupted by arroyos, the country is uniformly level, no hill breaking the 

 general view until we reach Eagle Pass ; and it may be that in time the resources of the 

 country will be sufficient to justify its connexion by railroad with San Antonio or Brownsville, 

 in which event the improvement of the navigation of the river will become of minor importance. 



Ascending beyond the mouth of the San Pedro or Devil's river, the whole character of the 



