Although the cañon at this point varies in width at the top from six to twelve miles, the river really runs through a narrow gorge, and partakes very much of the nature of a long rapid or cataract. For ten miles the fall averages twenty-one feet per mile, sufficient to make the current very dangerous even at low water, and something terrible after heavy rains or much snow melting. In one place the fall is eighty feet in about five hundred yards, and here, of course, navigation is practically out of the question. The explorers, to whom we have referred, were compelled to proceed with great deliberation at this point. Occasionally they ran the rapids, but very often they were compelled to lower their boats by means of lines, and even to lift them over exceptionally dangerous rocks. At the worst point of all, one of the boats, while being lowered by lines, was struck by an eddy and run tightly in between two rocks. It became necessary for men to go into the water to liberate the boat. With lines tied securely to their bodies, some of the boldest of the explorers ventured into the water and tried to loosen the boat, or at least to secure the invaluable provisions and blankets on board. It was January, and the water was so intensely cold that no man could endure it more than a few minutes at a time, so that the process was a long and tedious one. Finally the boat was got out, but it took five days to repair it, and even then it was a very poor means of navigation. A few days later, a still more powerful and dangerous rapid was encountered. Some idea of the force of the water can be gleaned from the precautions that were necessary. A line 250 feet long was strung out ahead, and the boat was swung into the stream. It went through apparently the most dangerous places without much difficulty. The line was loosened slowly and the boat held under control, but when it reached the main eddy it began to get contrary, and finally swung round, and seemed to have struck a back current. Several hours' work got the boat to shore, but the next one was dashed into a thousand pieces while crossing over some of the sharp-pointed rocks.