What the railroad did to the stagecoach, the automobile, aided by storm, did to the railroad. On December 11, 1937, as a result of prolonged and heavy warm rains which melted the early snow cover at elevations as high as 10,000 feet, a flood developed in the basins of Yosemite and Tenaya creeks, and to a lesser degree in the other Yosemite watersheds. The notch at the top of Yosemite Falls was filled almost to the brim with muddy water that was estimated to leap 150 feet away from the cliff at the top. In the valley itself Yosemite Creek was half a mile wide, and the Merced River overflowed its banks on a similar rampage. Flood scars were clearly visible in the chutes of the valley walls nine years later. In the Merced Canyon far below the valley several miles of both the All-Year Highway and the Yosemite Valley Railway were destroyed. The expense of replacing miles of twisted rails and missing roadbed, the loss of passenger traffic to automobile travel, and finally the loss of freight revenue when the Yosemite Sugar Pine Lumber Company sold its major holdings, combined to put the railway out of business. In 1945, wrecking crews took up the track, and another pioneer railroad disappeared. [Illustration: Horse-drawn stagecoach] CHAPTER VII _EXPLORERS_ The influx of travelers even in the days of horse trails and the stagecoach brought a demand to know more of the valley and the region as a whole. Maps were needed, and the desires of travelers for dependable information brought survey parties into the park. The first of these, the Geological Survey of California, was in Yosemite in the years 1863-1867. Josiah Dwight Whitney was director of the survey, and William H. Brewer, his principal assistant. A guidebook based upon their investigations was published in 1868. Most of the mapping was done by Clarence King, Charles F. Hoffmann, and James T. Gardiner. King was later to become the first director of the United States Geological Survey and to write a dramatized account of his adventures in Yosemite and the Sierra as one of the important contributions to the literature of the range, _Mountaineering in the Sierra Nevada_. Later mountaineers have not always been able to find terrain hazards he described but they have enjoyed his story, admittedly written for an armchair audience, and have made due allowance for an aspect of greater severity that existed in the Sierra of his day. A party of the Wheeler Survey, under George Montague Wheeler, in general charge of the Geographical Surveys west of the 100th Meridian, was in Yosemite in the late ’seventies and early ’eighties and in 1883 produced a large-scale topographic map of Yosemite Valley and vicinity. Lieut. M. M. Macomb was responsible for the Yosemite work.