OCR Text |
Show of alluvium at the time of the overflows, likewise aided by the winds collecting matter which has formed a backbone or elevation that now prevents the water from passing over. New River, and that called the Rio in Medio (Middle River), at the time of the overflow, water the basin. Middle River's mouth is a long distance above tidewater. Not so that of New River. The latter is caused by the backing up of the waters of the Colorado River by the tide of the Gulf of California at the time of the freshets, produced by the melting of the snows. The Colorado River runs at a velocity of 7^4 miles per hour, the Gulf tide at a velocity of lOj/2 miles an hour. Water runs through the Rio in Medio nearly every year, at any rate every freshet, but not in sufficient quantity to irrigate any great extent of country. Not so with New River; unless the freshet is sudden and great, the water does not reach farther than the Hog's Back, situated south and immediately in the vicinity of Purdy's, or Corro del Volcan, which causes a barrier to the further progress of the water through this channel (see section of New River bed on accompanying map). Since this survey was made of New River, the bed has filled up considerably south of the Hog's Back, where previously steamers have navigated as far as Promontory Point; that was the Embarcadero (landing) of that section of the country; here large quantities of sulphur were shipped on the steamer and forwarded to San Francisco. At this writing, however, even a light-draught stern-wheel steamer can not approach this landing within 400 yards, except at extreme high tides. This, as a matter of course, could be remedied by a little dredging at a small cost. The waters that could be supplied by these rivers (New and del Medio) could be used to very little ad- |