A geyser is a natural spring, which has an intermittent discharge of hot water, accompanied by steam. A geyser is created when the Earth's molten core heats a water source, rising it quickly to the surface. One of the most well known geysers is Old Faithful, which is located Yellowstone National Park, in the American state of Wyoming.
In 1850, as Daniel Clayton and Martha O'Brien crossed the Oregon Trail, they converged in northern Wyoming in what would later be Yellowstone National Park. When Doc, Jules, Verne, and Marty McFly visited, they recognized Old Faithful.