Sunday, February 3, 2008

Weathering Antarctica

Antarctica is a very windy continent. In the Dry Valleys, with so much loose rock and soil, wind has a big impact on the landscape. Weathering is the process by which wind and the atmosphere break down rocks and minerals. There are many types of weathering, but on Antarctica mechanical weathering from wind is the most common. When the wind blows, it picks up pieces of rock and soil and carries them through the air, often at very high speeds. These pieces of small rock and soil blow past and around other rocks. The friction of the soil and rock particles in the air rubs away at the rocks being hit by the small pieces. This is called abrasion. It causes the rocks here to take on very neat shapes!

The rocks that take on these cool, weathered shapes are called ventifacts. They have been worn down, grooved, and polished by the wind and the grit it carries. Ventifacts are very common in dry, desert environments. We see lots of ventifacts of all shapes and sizes in the Dry Valleys. Here is a particularly cool one that we found around Lake Bonney last week that Elizabeth is using as her throne!
The soil, sand, and rock that are blown around by the wind don't always remain on land. Sometimes soil is blown onto nearby sea or lake ice, creating what is called "dirty ice." The soil absorbs and holds more warmth than ice, causing the ice beneath the soil to melt faster than neighboring uncovered ice. There is a large patch of dirty ice near the entrance to Garwood and Marshall Valleys. We have flown over it several times now!
Our time on the Ice is coming towards a close soon! We fly away from McMurdo on Tuesday. That means we have one more full day on station to get the rest of our work done and soak up the Antarctic scenery. We have a lot to do!


  1. thats pretty cool, nice pics :D

  2. actually weathering refers to the breakdown of rocks in situ. You are referring to wind erosion. Amyway love the pictures.

  3. Hi anonymous,

    You are partially correct. Yes, weathering and erosion are closely linked, yet not the same thing. Weathering refers to the gradual breaking up and disintegration of a rock in contact with the atmosphere. Erosion refers to the transfer of the weathered material. The large rocks being hit by the wind-blown particles are being weathered through abrasion, a form of mechanical weathering. The chunks that are blown away from the weathered rock are undergoing erosion.