Midway Geyser Basin is a collection of springs and geysers along the Firehole River in Yellowstone National Park and it is also the location of the Grand Prismatic Spring. At 370 feet across and 120 feet deep, it is considered the largest hot spring in the United States and third largest in the world. It was named by the Hayden Expedition in 1871 due to the bright coloration that is due to cyanobacteria and crystallized minerals. Thomas Moran made water-color sketches but geologist A.C. Peal thought they were exaggerations and he returned in1878 to verify the colors. The spring is continuously bubbling and forming clouds of steam as it discharges about 560 gallons of water per minute into the Firehole River. |
