Pressure Ridges Tour

December 12, 2013

Scott Base, Antarctica

Pressure ridges are linear features in the ice caused by the collision of the ice shelf and sea ice.  I could see the pressure ridges from the top of Observation Hill, from which this photograph was taken.  Later that evening, we got a chance to walk around the ridges for two hours with a guide from McMurdo.

Scott Base, the New Zealand station, and pressure ridges on the far side of the station

Flags marked the areas where it was safe to walk.

You have to be careful where you walk to avoid falling in cracks

These don't look quite big enough to fall down.
The ice is actually much thicker, but this water has been squeezed up the crack.

Phase 1 of the growth of pressure ridges, starting subhorizontal

Phase 2: this ridge is perfectly vertical.  The guide says it used to be standing straight up.
He can see changes in the pressure ridges within a week.
This ridge is about 3m tall.  Ridges have been measured up to 5m tall.

These pools are also filled with water from the sea below.
In Antarctica, there is barely any surface melt since it rarely breaks freezing temperatures.
The water appears slightly brown because protists (foraminifera) live in the water.

Tiny salt and water crystals form on the top of these pools.

In the center of this photo, you can see that the ice appears a turquoise shade of blue.
This is due to the crystalline structure of ice, which scatters blue light

Mount Erebus, an active volcano, to the south

This seal has teeth marks on his torso - most likely from a lost fight over a female seal.
White Island is visible in the background.

Seals dot the landscape.  White Island on the left, Black Island on the right.
Naming is a bit lacking in creativity, but I'm sure it made navigation easier.