The Tidal Bore 
159 
bar close under our lee broke the wave into several long swells, and 
as these met the ebb the broad sheet around us boiled up and foamed 
like the surface of a cauldron, and then, with scarcely a moment of 
slack water, the whole went whirling by in the opposite direction. 
In a few moments the low rollers had passed the islands and united 
again in a single bank of water, which swept up the narrowing 
channel with the thunder of a cataract.” 
This was the great tidal bore once more, which, at the occur¬ 
rence of the spring tides, makes the entrance of the river ex- 
Robinson’s Landing. 
Mouth of the Colorado River. Starting-point of Lieut. Ives’s Exploration. 
Photograph by Lieut. Ives. Redrawn by J. J. Young. 
tremely dangerous. It is due to the narrowing of the Gulf of 
California forcing the tides into close quarters, and its vio¬ 
lence is augmented by collision with the equally furious current 
of the Colorado. The battle between this tidal wave and the 
Colorado continues for many miles, till at last the sea tide 
gradually loses its power and succumbs to the flood of the 
river.^ The latter falls at the mouth, according to Ives, about 
^ The tide ascends thirty-seven miles. Lowest stage of water about three feet, 
average six feet, and highest about twenty feet. 
