McMurdo Dry Valleys

As Antarctic dry valleys (English: Antarctic Dry Valleys or McMurdo Dry Valleys ) refers to a series of ice-free valleys ( an Antarctic oasis ) in Victoria Land East Antarctica. The largest are Victoria Valley, Wright Valley and Taylor Valley. Due to the prevailing extreme conditions, a unique landscape has evolved with unique creatures.

Location

The valleys are a part of the Transantarctic Mountains, which runs through the Antarctic over a length of about 4000 km. They are located on the western coast of McMurdo Sundes over the Ross Island. Considering together all the valleys, so they have a north- south extent of about 70 km and a maximum east - west distance of 70 km also. In total, they cover an area of about 4900 km ². The Antarctic dry valleys start at about 77 ° 15 ' South and end at approximately 77 ° 45' South, also they are between about 161 ° East and 163 ° East. The Taylor Valley extends furthest to the east ( approximately to 163 ° 30 'East ), the Victoria Valley and Wright Valley, however, go further to the west ( 160 ° 30' East).

Dry valleys - Overview

• Alatna Valley is the most northerly, north of Bensongletschers.

The three main valleys from north to south are:

• Victoria Valley ( between St. Johns Range in the north and Olympus Range in the south)
• Wright Valley ( between Olympus Range in the north and Asgard Range in the south)
• Taylor Valley ( between Asgard Range in the north and Kukri Hills to the south )

West of Victoria Valley are, from north to south:

• Barwick Valley
• Balham Valley
• McKelvey Valley

Located west of the Taylor Valley

• Pearse Valley ( sometimes incorrectly referred to as Pearce Valley )

Further south, between the Royal Society Range in the west and the west coast of McMurdo Sundes lie at the snout of the glacier Koettlitz, from north to south:

• Garwood Valley
• Marshall Valley
• Miers Valley

The Victoria Valley is the northernmost and has a length of approximately 40 km. Thus, it is also the smallest of all three valleys. To the south is the mountain range Olympus Range, which is also free of ice for the most part and has a maximum height of 2180 m.

The Wright Valley, which lies south of the Olympus Range, has a length of 60 km; striking here is that there is wider with an average of 8 km than the other valleys (2 km on average) and lower in altitude has. To the south, the valley rises to the Asgard Range, which is, however, in places covered with snow. This mountain range has a maximum altitude of 2410 m. Through the Wright Valley flows with the Onyx the longest river in the Antarctic.

The Taylor Valley is about 50 km long. Unlike the Wright Valley and Victoria Valley, which open to the sea in the Wilson Piedmont Glacier, Taylor Valley ends right in McMurdo Sound. This makes it easier to reach than the other valleys and therefore the most popular for research.

Climatic conditions

The climatic conditions of the dry valleys are among the most extreme of the earth. During the Antarctic winter, temperatures drop below -50 ° C, even in summer it can reach more than -10 ° C, is extremely rare temperatures around the freezing point of 0 ° C. At the former New Zealand Vanda Station on the same lake in Wright Valley, however, the highest ever measured in the Antarctic temperature has been reached on January 5, 1974 15.0 ° C. From land breeze all year often gale-force winds that split rocks and boulders and destroy. Only very rarely bring them with even some snow from the glaciers. The Antarctic dry valleys are dry and hostile than the Atacama Desert in Chile or the Sahara.

One consequence of these conditions is the fact that the soils are extremely salty. Thus one finds in some areas of standing water that can not freeze due to the high salt content.

Reasons for the extreme conditions

The main reason for these extreme conditions is the location of the Transantarctic Mountains. This mountain range protects the valleys from the continental ice of East Antarctica. The glaciers are stopped by the mountains and the sea can not, for example, to McMurdo Sound, penetrate.

The continental ice is not reached on the one hand often the same height as the peaks of the Transantarctic mountain range. The winds that now flow over the continental ice to the mountains lose their snow on the peaks of the mountain range. Once this limit is exceeded, the dry winds fall off sharply and blow through the valleys to the sea. Due to their drought "suck " the winds out the last moisture from the valleys.

However, the above conditions apply only to the Antarctic dry valleys, in other regions they are only partially applicable. In other parts of the Transantarctic Mountains is broken much more so that the Antarctic continental ice can flow over the mountains across the sea; in such areas often protrude only the peaks of the Arctic Ocean. Also, the continental ice in other regions of the Transantarctic Mountains suppressed with a much higher pressure against the mountain range.

Ecology

The ecological conditions of the region are unique worldwide. However, an ecological life is not playing on the surface of the valleys themselves, since the conditions are too extreme, than that a nutrient cycle could develop. In the dry valleys, however, some lakes have held that are up to 80 m deep and are frozen for millions of years for the most part. However, these lakes thaw on the shore edges on with millimeter-sized gaps in November, so that life there has a chance to existence. But the Onyx River and puddles of water that do not freeze well because of their salt content, harboring microscopic life.

Waters

Lakes

Some of the lakes are among the most saline waters of the earth, with a higher salt content than the Lake Assal, or the Dead Sea. This list is led by small Don Juan Lake in Upper Wright Valley, 9 km west of Vandasees.

• Vidasee (Victoria Valley)

• Vandasee ( Wright Valley)
• Brownworthsee ( Wright Valley) (freshwater)
• Don Juan Lake ( Wright Valley)

• Fryxellsee (Taylor Valley)
• Hoaresee (Taylor Valley)
• Lake Chad (Taylor Valley)
• Dirty Little Hoare Pond ( Taylor Valley)
• Parera Pond ( Taylor Valley) (freshwater)
• Bonneysee (Taylor Valley)

• Housesee ( Pearse Valley)
• Joycesee ( Pearse Valley)

• Garwoodsee ( Garwood Valley)
• Mierssee ( Miers Valley)

Watercourses

• Kite Stream (Victoria Valley)
• Onyx River ( Wright Valley)
• Vincent Creek ( Taylor Valley)
• Crescent Stream (Taylor Valley)
• Harnish Creek ( Taylor Valley)
• Huey Creek ( Taylor Valley)

Research

For the research, the Antarctic dry valleys are highly interesting. The local Critters come so only in the valleys. In addition to studying the ecology of fossils play a major role. These have been in the air frozen and perfectly preserved. NASA also is interested in the valleys, as they are similar to the structure of the Martian surface. In November 2012, researchers reported after sampling from Lake Vida on detection of at least 32 different extremophile bacteria variants that could be assigned to eight different strains.

Fiction

In 1997 published novel by American writer Antarctica Kim Stanley Robinson the dry valleys are an important action scene.