Ice on the Move...

February 4, 2023

Today was another get up, put on our cold weather gear, and get on a Zodiac day. This was a scenic Zodiac cruise. We cruised around Chiriguana Bay at a slow speed to look at the beautiful landscape and scenery of Antarctica; and, it was magnificent! And our guide provided an interesting and informative discussion about glaciers and icebergs. We learned a lot and grew to really appreciate the power of nature.

So, where do icebergs come from? Icebergs are formed when a piece of a glacier breaks off and lands in water below.That leads to the question - what is a glacier? A glacier is a thick river of ice that is moving slowly downhill as it is pulled by gravity. The glacier is formed by an accumulation of ice, snow, and water over many years. And when viewed as a cross-section, there are layers visible in the glacier that show annual accumulations. As the glacier moves over the ground, it picks up rocks, dirt and boulders underneath, and also pushes those things out in front of the glacier. The rocks and boulders that precede the glacier are called the moraine.

The uneven area on the left is a moraine, the part on the right is a glacier

Not all the snow-covered areas in Antarctica are glaciers. Observing from the water, the gently sloping snow-covered hills, are just that – snow on the ground. Sometimes that snow may slide down into the water, gently or as an avalanche.

When a large piece of ice falls off from a glacier and lands in water, it is an iceberg. Places where the ice recently left the glacier, and on the parts of the iceberg that hadn’t been exposed before it broke off, may appear blue. This is because those are places that have been protected from exposure to snow for a long period of time. Snow contains air bubbles and crystal edges that reflect all colors of light, which makes most ice appear white. Over the years as the ice compresses under new layers of snow, the pressure collapses the air bubbles and the snow turns into ice. Now the ice is snow free and only reflects blue light.

Over time the iceberg undergoes changes. They can change shape, flip over, break apart, and more. Here are some examples:

A piece of an iceberg less than 16 feet above sea level is a Bergy bit.

A piece of an iceberg approximately 6-10 feet above water is a growler.

Brash ice is an accumulation of floating ice made up of fragments 6 feel across or less.

A tabular berg is a flat top iceberg.

Here is our final picture that shows two different types of ice formations that we have discussed above.

Based on what you have read, what do you see in this picture?

We were able to participate in a submarine dive today. Remember to check our blog again for details.