McMurdo Dry Valleys

The McMurdo Dry Valleys sit on the Victoria Land coast of Antarctica, between the East Antarctic Ice Sheet and McMurdo Sound, covering roughly 4,500 square kilometers, about 0.03 percent of the continent, and forming the largest ice-free area in Antarctica. They stay free of snow and ice through two combined effects: the Transantarctic Mountains cast a snow shadow that limits precipitation to around 100 millimeters a year, and powerful katabatic winds descending from the polar plateau evaporate what little snow falls, sometimes within hours in summer, before it can melt into the soil. The exposed basement rock includes Late Precambrian to Early Paleozoic metamorphic rock such as the marble and calc-schist Asgard Formation, intruded by Paleozoic granite during the Ross orogeny, capped in places by the Jurassic Beacon Supergroup sandstone and by Ferrar Dolerite sheets, with young basaltic cinder cones from the McMurdo Volcanic Group dated between 2.1 and 4.4 million years old. Within the valleys, Blood Falls releases iron-oxide-stained water from beneath Taylor Glacier into Lake Bonney, and nearby Lake Vida has recorded temperatures as low as minus 65.7 degrees Celsius. This entity documents the Dry Valleys specifically as a geological formation shaped by wind erosion and glacial retreat under an extreme cold desert climate.