During the travel season of 1959, Yellowstone was host to 1,489,112 visitors. This multitude exceeded the total of all persons entering the Park in the first half century of its existence. Facilitating their enjoyment and at the same time preserving the domain as a pleasuring ground for their descendants requires a good measure of understanding on the part of the public, together with a high degree of understanding and training upon the part of the officials. Earth tremors are common in the Yellowstone region. The Hayden Survey reported feeling severe shocks near Steamboat Point on Yellowstone Lake in 1871. They named the site “Earthquake Camp.” Other quakes have been reported, mostly of a minor nature. At 11:38 p.m. on August 17, 1959, an earthquake of magnitude 7.1 on the Richter Scale struck the Yellowstone area. The epicenter of the quake was along the western boundary of the Park in the vicinity of Grayling Creek. The greatest earthquake damage took place in the Madison Canyon about 7 miles below Hebgen Dam and outside Yellowstone. A massive slide of about 80 million tons of earth and rock blocked the canyon and entombed a number of campers along a half-mile stretch of the Madison River. This natural dam has created Earthquake Lake, a feature that will attract attention for years to come. In Yellowstone National Park dangerous rock slides covered Park roads at several points along the Madison, Firehole, and Gibbon rivers, and at Golden Gate. Tall chimneys toppled from Old Faithful Inn and other Park buildings, and there was structural damage to many roads and buildings. The hot springs showed a greater change in this one night than had been observed in the entire history of the Park. Close study of the thermal features revealed that most springs had discharged water copiously during the quake and aftershocks, and then ebbed below normal levels. Investigation revealed that at least 298 springs and geysers had erupted the night of the quake, and 160 of these were springs with no previous record of eruption. Other changes occurred slowly. The Fountain Paint Pot did not manifest unusual activity until several days after the quake, but then encroached upon walks and parking areas. Most of the hot springs became turbid, and even cold springs that fed the mountain streams on the west side of the Park discharged an opaque mud which discolored the creeks and rivers. Equilibrium was gradually restored in the geyser basins. Some of the earthquake changes were permanent, others transitory. All of them make this chapter in the living geology of Yellowstone an intensely interesting one for Park visitors to learn about.