Old Faithful Geyser is historically perhaps the most famous feature in Yellowstone, if not of any national park. Members of the 1870 Washburn Expedition named the geyser because of it persistent and regular schedule of eruptions that typically last between 2 to 5 minutes and repeat every 40 to 100 minutes (depending on the size and duration of previous eruptions). The height of the spray ranges from about 100 to 200 feet, but the steam cloud can rise much higher, especially on a cold, still winter day (Schreier, 2005).