The McMurdo Dry Valleys are a group of mostly snow-free desert valleys located on the coast of Victoria Land, Antarctica. They are east of the East Antarctic Ice Sheet and west of McMurdo Sound and the Ross Sea. These valleys are well-known as the coldest and driest desert on Earth, and they are the largest area in Antarctica without ice. Because of this, scientists often study the region to learn more about Antarctica. The unique climate of the Dry Valleys is caused by their position within the Transantarctic Mountains and strong, high-pressure winds called katabatic winds, which blow down from the mountains and remove snow and moisture. Nearby mountains stop ice from glaciers from moving into the valleys. The area’s rock is mainly made of granite and gneiss, and glacial tills cover parts of the bedrock. Loose gravel also lies on the ground. Although the valleys are extremely dry, some people have reported seeing rain in the area.
The region includes several features, such as Lake Vida, a salty lake, and the Onyx River, a stream formed by melting ice and the longest river in Antarctica. No living things have been found in the frozen ground here, but tiny bacteria that live inside rocks and use sunlight to grow have been discovered in the wetter parts of the rocks. Other bacteria that do not need oxygen and use iron and sulfur for energy have been found under Taylor Glacier.
The valleys are part of the McMurdo Valleys Antarctic Specially Managed Area (ASMA-2).
Climate
The Dry Valleys are one of the most extreme places on Earth and are considered a cold desert. They cover about 4,500 square kilometers (1,700 square miles) and make up about 0.03% of Antarctica. This area is the largest part of Antarctica without ice.
The Dry Valleys receive very little rain or snow because of the Transantarctic Mountains, which block the movement of moisture. These mountains are up to 3,000 meters (9,800 feet) high. As a result, the valley floors are often uncovered and covered with loose gravel. Some areas show patterns of ice wedges in the ground.
The unique conditions in the Dry Valleys are partly caused by katabatic winds. These are strong, cold winds that flow downhill because of gravity. These winds quickly remove snow and prevent much of it from melting into the soil. In the summer, this process can happen in just a few hours.
Another key factor is the lack of precipitation. Over 100 years of records show that the area receives about 100 millimeters (4 inches) of snow each year. This low amount of snow contributes to the area’s very dry air.
Even though there is little snow or ice on the surface, the Dry Valleys have more than 6,000 lakes and ponds.
During the summer, temperatures rise enough to cause glaciers to melt, forming small streams of freshwater. These streams flow into lakes at the bottom of the valleys. Because these lakes do not connect to the sea, the water becomes very salty.
The highest and lowest air temperatures recorded in the McMurdo Dry Valleys (MDVs) were 12.0°C (53.6°F) at Taylor Glacier and −65.7°C (−86.3°F) at Lake Vida, respectively. The average yearly air temperature on valley floors ranged from −14.7°C (5.5°F) at Lake Bonney to −29.6°C (−21.3°F) at Lake Vida. In Taylor Valley, which has eight stations, the average yearly temperatures on valley floors ranged from −14.7°C (5.5°F) to −23.0°C (−9.4°F). The four stations on glaciers had average yearly temperatures from −15.1°C (4.8°F) to −19.4°C (−2.9°F).
At higher elevations, temperatures ranged from −20.7°C (−5.3°F) to −25.2°C (−13.4°F). When comparing the average yearly temperatures of the valleys using valley floor stations, from warmest to coldest, the order is: Miers Valley −16.5°C (2.3°F), Taylor Valley −18.5°C (−1.3°F), Wright Valley −19.8°C (−3.6°F), and Victoria Valley −26.8°C (−16.2°F).
Geology
The McMurdo Oasis is surrounded by the coastline of south Victoria Land and the Polar Plateau. The Taylor and Wright Valleys are important ice-free valleys located within the Transantarctic Mountains. These "dry valleys" contain hummocky moraines, frozen lakes, saline ponds, sand dunes, and meltwater streams. The basement rocks include Late Precambrian or Early Palaeozoic Skelton Group metamorphic rocks, mainly the Asgard Formation, which is a medium-high-grade marble and calc schist. The Palaeozoic Granite Harbour intrusives consist of granitoid plutons and dykes that formed when they were pushed into the metasedimentary Skelton Group during the Late Cambrian to Early Ordovician period as part of the Ross orogeny. The basement complex is covered by the Jurassic Beacon Supergroup, which is itself cut through by Ferrar Dolerite sheets and sills. The McMurdo Volcanic Group is found within or between the moraines of the Taylor and Wright Valleys as basaltic cinder cones and lava flows. These basalts are between 2.1 and 4.4 million years old. The Dry Valley Drilling Project (1971–75) found that the Pleistocene layer in Taylor Valley was between 137 and 275 meters thick and made up of layered sandstones, pebble conglomerates, and laminated silty mudstones. This Pleistocene layer lies above Pliocene and Miocene diamictites.
Research
Since the Dry Valleys were discovered in the early 1900s and research stations like McMurdo Station (United States) and Scott Base (New Zealand) were built on Ross Island in the 1950s, scientists have studied the region extensively. The valleys' very dry and cold climate was quickly recognized as a similar environment to Mars. Scientists have used the Valleys as a testing ground for Mars-related research since NASA's Viking Program in the 1970s.
In 1985, the first continuously operating weather station was placed at Lake Hoare. In 1992, Taylor Valley, the southernmost of the three major Dry Valleys, was chosen as a National Science Foundation Long Term Ecological Research (LTER) site. This allowed scientists to study ecological processes over many years. As of August 2025, there are 26 real-time weather stations, stream gauges, and observing platforms, and 1,028 scientific papers connected to the LTER program.
In 2013, Irish and American researchers visited University Valley to study microbes and test a Mars-like drill in the driest parts of the valleys, which are most similar to Mars. They found no living organisms in the frozen ground, making University Valley the first place on Earth where humans found no active microbes.
Scientists have also studied ice-covered lakes and streams in the valleys. These lakes have thick ice because of cold temperatures, but they also lose ice through sublimation and gain water from melting glaciers.
Microbial mats have been found in streams, lakes, wetlands, and ice in the region. These mats are unique because strong winds constantly remove material from them.
Endolithic bacteria live inside rocks, protected from the dry air by the moist interior of the rocks. Nutrients in the soil come mainly from summer glacier meltwater.
Anaerobic bacteria that use iron and sulfur for energy live under Taylor Glacier in freezing temperatures.
It was once believed that algae caused the red color of ice at Blood Falls, but scientists now know the red color comes from high levels of iron oxide.
In 2014, scientists from Auckland University of Technology used drones to map plants in the McMurdo Dry Valleys. In 2015, the New Zealand Antarctic Research Institute funded the team to develop drone technology. Over several summers, the team created 3D maps with very high detail, which are now used as reference points.
Part of the Dry Valleys was made an environmentally protected area in 2004.
Major geographic features
From north to south, the three main valleys are:
West of Victoria Valley, from north to south, are:
Stretching south from Balham Valley, from west to east, are:
West of Taylor Valley is:
Further south, between the Royal Society Range in the west and the west coast of McMurdo Sound at the lobe of Koettlitz Glacier, from north to south, are:
Some of the lakes in the Dry Valleys are among the saltiest lakes in the world, saltier than Lake Assal or the Dead Sea. The saltiest of all is the small Don Juan Pond.