GEOLOGY

Detailed explanation-1: -Old Faithful erupts more frequently than any of the other big geysers, although it is not the largest or most regular geyser in Yellowstone National Park.

Detailed explanation-2: -Old Faithful was named by the Washburn Expedition of 1870, who explored the area that would later be called Yellowstone. Members of the expedition entered the Upper Geyser Basin after traveling down the Firehole River and saw the geyser, which they called Old Faithful because of the regularity with which it erupted.

Detailed explanation-3: -Old Faithful-Yellowstone National Park (U.S. National Park Service)