A Hike and Tour of the Pressure Ridges
Written by Betty Trummel
A group of WISSARD’s went out early this morning with a guide, Todd, to view the pressure ridges close to Scott Base. Pressure ridges form when the sea ice collides with the glacial ice of the ice shelf. The pressure of those two masses of ice coming together makes some of it lift up into unique and beautiful ice/snow formations. These almost look at times like ice waves. We spent several hours out on the ice hiking and observing seals.
Weddell seals come through the cracks in the ice or a melt pool (ice that is now melting on our warmer days) and lounge around on the ice. The first seal we saw was quite a poser!
They have a sweet face and it almost looks like they are smiling!
The seals would wake up occasionally and wiggle their tail flippers. They’ll also scratch themselves with their arm flippers. Our WISSARD videographer, Dave, filmed a lot of the seal behavior and the ice waves of the pressure ridges throughout our hike.
It was a cloudy day today (warm, about 35 degrees F) and the ice took on a rather blue quality. Some of the melt pools freeze back up when temperature drops. The photo below shows how beautiful these frozen pools can be. Ribbons of blue and white curve gently through the frozen pool.
In other areas, we’d see icicles hanging down off of huge ice shelves. The patterns and shapes of these pressure ridges change every day. Todd mentioned that he’s led several hikes here now and each time the pressure ridges have looked completely different.
Todd went through a special training session to be able to lead these hikes. He was always ready to alert us about cracks in the ice. The flags mark the route and also show where danger might exist. If two flags are together around a crack, they can help tell how much that crack is spreading or closing over a given number of days.
The flags shown here mark the end of the side trail we took to reach this frozen pool. I thought the colors and shapes were fantastic, and I liked the cloudy weather instead of a bright glare on the ice and snow.
As we hiked along, we could see Scott Base not far away.
Here are a few more photos, and be sure you read all the way to the end of this post. I have a special short video to share!
This picture illustrates how tall the pressure ridges can be compared to my height.
Often we couldn’t get that close, due to the danger of cracks and uneven ice.
Dave hauled his heavy camera to get some incredible shots. I can’t wait to see those images and the videos.
Later today there was a McMurdo “event” of sorts. Many people in the town came out both yesterday and today for a blast taking place near the ice pier. It was like a social event!
Right now they are freeing up ice around the pier with explosions, and workers will gently move the ice pier closer toward the road. The dirt you see on the flat platform is actually covering a thick layer of ice. Creating the ice pier takes a ton of work! It has to be up to 22 feet thick and strong enough to support container trucks. The McMurdo ice pier is approximately 800 feet long and 300 feet wide. Usually an ice pier has a life span of 3-5 years and once it is no longer stable it is towed out to sea, cast adrift, and a new ice pier is created.
When the re-supply ship comes in later this season (February), it will dock next to this pier and cranes will off-load heavy containers while every truck and vehicle possible will help deliver materials and equipment to places here in McMurdo. Here is a short video of today’s blast….it was SO loud, which I am not sure you catch on this video.