was , which makes it the world's warmest 24-hour temperature on record. Four major mountain ranges lie between Death Valley and the ocean, each one adding to an increasingly drier rain shadow effect, and in 1929, 1953, and 1989, no rain was recorded for the whole year. The period from 1931 to 1934 was the driest stretch on record, with only of rain over a 40-month period. The average annual precipitation in Death Valley is , while the Greenland Ranch station averaged . The wettest month on record is January 1995, when fell on Death Valley. The wettest period on record was mid-2004 to mid-2005, in which nearly of rain fell in total, leading to ephemeral lakes in the valley and the region and tremendous wildflower blooms. Snow with accumulation has only been recorded in January 1922, while scattered flakes have been recorded on other occasions. Flooding In 2005, Death Valley received four times its average annual rainfall of . As it has done before for hundreds of years, the lowest spot in the valley filled with a wide, shallow lake, but the extreme heat and aridity immediately began evaporating the ephemeral lake. The pair of images (seen at right) from NASA's Landsat 5 satellite documents the short history of Death Valley's Lake Badwater: formed in February 2005 (top) and evaporated by February 2007 (bottom). In 2005, a big pool of greenish water stretched most of the way across the valley floor. By May 2005, the valley floor had resumed its more familiar role as Badwater Basin, salt-coated salt flats. In time, this freshly dissolved and recrystallized salt will darken. The western margin of Death Valley is traced by alluvial fans. During flash floods, rainfall from the steep mountains to the west pours through narrow canyons, picking up everything from fine clay to large rocks. When these torrents reach the mouths of the canyons, they widen and slow, branching out into distributary channels. The paler the fans, the younger they are. Ecology In spite of the overwhelming heat and sparse rainfall, Death Valley exhibits considerable biodiversity. Flowers, watered by snowmelt, carpet the desert floor each spring, continuing into June. Bighorn sheep, red-tailed hawks, and wild donkeys may be seen. Death Valley has over 600 springs and ponds. Salt Creek, a mile-long shallow depression in the center of the valley, supports Death Valley Pupfish. These isolated pupfish populations are remnants of