Geothermal areas of Yellowstone#Norris Geyser Basin

The Norris Geyser Basin is the hottest geyser basins of Yellowstone National Park. It is located on the northwestern edge of the caldera of the Yellowstone volcano, near the village of Norris Junction in the U.S. state of Wyoming. The Norris Geyser Basin is home to the Steamboat Geyser the largest active geyser in the world.

In the Norris Geyser Basin, three major faults intersect. The Norris - Mammoth Corridor is a fault that runs from Norris by Mammoth Hot Springs to Gardiner. The Hebgen Lake fault begins in the northwest of West Yellowstone and ends in Norris. These two faults intersect with an annular breaking point, resulting from the volcanic eruption 640,000 years ago. These faults and associated fractures, can circulate through the hot water, are the reason why the pool is so hot.

Compared to other Geyser Basin National Park most of the water is in the Norris Basin acidic and not basic. There are even some geysers with acidic water, which is very rare. The pH of the Echinus Geyser is about 3.5. The acidic water allows other bacteria in the hot springs of life. Therefore, the sources in the Norris Basin in a color different from the other sources.

The Ragged Hills in the Norris Geyser Basin are hydrothermally altered glacial moraines. As the glaciers retreated after the last ice age melted the underlying hydrothermal activity the remains of the ice masses, leaving behind deposits. Steam and hot water deformed them. The town of Madison is located within the eroded river channels of the lava flows of the last volcanic eruption. Both the Gibbon Falls and the Virginia Falls lie on the rim of the caldera.