Friday, 20 October 2017

Glaciers and Icebergs

Pius XI Glacier
Having missed seeing the tidewater glaciers in Laguna San Rafael and in Seno Iceberg due to weather issues, we really wanted to see at least one Chilean Glacier on this voyage. We have, of course, seen many glaciers that calve ice into the sea in previous voyages to Chile, Alaska, Antarctica, Norway and Greenland ... but memories are not the same as seeing something NOW.

The Pío XI glacier, named after Pope Pius XI, represented a diversion of some fifty miles round trip just south of Puerto Eden and, more importantly, a brief two day period of reasonable weather was available for the viewing. It involved a punishing slog up the fjord against twenty knots of wind and cold rain but this all cleared up, as expected, just as we arrived.

Pío XI presents quite a varied spectacle. First, it is immense, measuring around four kilometers across its snout which is fifty meters high above the sea. At first viewing from a distance of 30 km as we turned into Seno Eyre we could see the top of the glacier as it flowed down from the Patagonian Icecap. The concept of ice "flowing" downhill was obvious with two lines of dirty rocks ground from the fjord walls drawn along the upper surface along with other flow lines that gave the ice a bit of the appearance of white plastic from that distance.

As we got closer, the upper surface disappeared, hidden by the height of the forward face.

Glaciers on the land melt at their lower elevations in a much less spectacular way than tidewater glaciers. A glacier that ends in the sea is melted rapidly from underneath by the sea. It then loses support and large volumes of ice crash spectacularly into the water. This is accompanied by a noise like nearby thunder or an explosion and very large waves. We were able to witness this from a quarter mile away ... which felt quite close enough.

In order for a glacier to produce large icebergs, the water at its face must be deep enough to float them away. With two hundred meters of water at the face, very large icebergs can be calved from the glacier as in Greenland or Antarctica. Pío XI sheds a lot of ice into the water, as evidenced by the care and effort involved in dodging all the chunks while navigating to and from the glacier. Nonetheless, the pieces are not large - no more than perhaps six meters across or about 100 tons - because the depth at the face is only about 30 meters or less. In fact, as can be seen in the photo, parts of the face are out of the water now, having emerged onto a terminal moraine. While this is perhaps not as attractive as a completely tidewater glacier, the variety presents an interesting study.

It is difficult to put into words the incredible magic of the scene here. Fine days are rare enough that they are treasured. The sky is blue; the winds are light; dolphins play among the floating blocks of ice.
In places, the surface of the water is so calm we can see those dolphins playing three meters beneath our bow, so sleek that the smallest wiggling motion with their tails sends them along at the speed of our boat with its powerful diesel engine.

The walls of these channels are carved out of enormous single rocks reaching the sky - sparsely covered in their lower levels by forest struggling for existence against the typically fierce weather. The heights are snow covered. The bright sun shining through the very clear air shadows the fissures in the rocky shores with a sharp contrast. And everywhere you look, myriad waterfalls carve silver lines into the mountain sides. What a day!

But we must hurry on on a day like this. The forecasts show a fifty knot storm in the open ocean by tomorrow evening. While it is true we are in relatively sheltered waters, we need to tie ourselves to many trees in a tiny cove to achieve a measure of safety. This type of storm blows fierce and gusty through the channels and we must hide from it.

At 2017-10-20 17:26 (utc) our position was 49°52.20'S 074°22.79'W

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