On the west bank of the Canal occurred a slide of the second type caused by the crushing and squeezing out of underlying layers of soft material by the prodigious pressure of the high banks left untouched by the steam shovels. This slide is usually accompanied by the uprising of the bed of the Canal sometimes to a height of thirty feet. Col. Gaillard tells of standing on the bed of the Canal, observing the working of a steam shovel, when it gradually dawned upon him that he was no longer on the level of the shovel. At first he thought that the shovel must have been placed upon a bit of boggy land and was slowly sinking, but on investigation he discovered that the point on which he was standing had been slowly rising until within five minutes he had been lifted six feet without jar and with no sensation of motion. A perfectly simple illustration of the way in which this elevation of the bed of the Canal is caused may be obtained by pressing the hand upon a pan of dough. The dough will of course rise at the side of the hand. On the “big job” the towering hills furnished the pressure, the bed of the Canal rose like the dough. In the diagram already referred to, the slide to the right marked “B” is of the type here described. To cope with it, the work of the shovels and dirt trains in the Canal carrying the débris away is supplemented by others above removing the crest of the slide and thus lightening the pressure. In the diagram shovels are shown thus working on two levels, but I have seen four terraces of the same slide bearing steam shovels and rumbling dirt trains hurrying the débris away to where it will no longer be a menace. [Illustration: DIAGRAM OF CULEBRA CUT SLIDES C. is a slide moving over a slippery surface; the mass B breaks on a line of cleavage and crushes the underlying material, forcing it up at A. The steam shovels are working to reduce pressure on B] [Illustration: _Courtesy of Scientific American_ A ROCK SLIDE NEAR EMPIRE About 400,000 cubic yards of rock broke away, half filling the cut and opening it to the water of the Obispo Diversion Canal]