The Stikine Icefield

Part of our recent survey took us down to the Stikine Icefield, Alaska's southernmost icefield. Its southern location and relatively low elevation make it vulnerable to changing climate, but this can be offset by high rates of snowfall. The icefield has several glaciers that reach the ocean, among them LeConte Glacier, the southernmost tidewater glacier in the northern hemisphere. Many of the tidewater glaciers have retreated very rapidly in the past few years.

The icefield is spectacular with many impressive spires, most famously Devil's Thumb.

Sawyer Glacier calving into a very narrow fjord

The famous Devil's Thumb with Cat's Ears and Witches Tit to the right.

Devils Thumb through a gap

Witches Cauldron: This is a really weird place where glaciers flow in from several sides and just kind of disappear. It's where glaciers go to die...

Devil's Thumb with shadows of the Cat's Ears

Burkett's Needle

The picturesque fishing town of Petersburg

What are you looking at?

Dawes Glacier (I think). The trimlines show the extent of recent ice loss

A cruise ship in Tracy Arm

Surging glaciers

While we were surveying glaciers in several mountain ranges, we had the opportunity to watch a vast variety of glaciers. While many are rapidly retreating, some are advancing and a few are experiencing a glacier surge. This is a phenomenon where a glacier increases its speed by a factor of ten or more for several months. It only happens on very few glaciers. Glacier surges happen periodically, every few years on some coastal glaciers and every few decades in the Alaska Range. So it's always a special treat to see one.

Turner Glacier (coming straight at us, across the bay) is the only tidewater glacier in Alaska that is surging. It has an unusually quick repeat cycle and this is its third surge in the last ten years.

The broken surface of Turner Glacier near its front

We noticed unusual crevasses on the Logan Glacier in March, and now they are even more pronounced.

The surge does not produce crevasses across the entire glacier, but there are distinct crevassed bulges on the side that indicate fast flow.

Logan Glacier

This is the Robertson or the Johnson Glacier in the Alaska Range. It is not known to surge, and I don't believe this is a real surge. But that fresh shear crevasse running along several kilometers is something I've never seen before on a glacier.

Avalanches

One of the amazing things on this last trip was the very large number of avalanches that we saw, wherever we went. There were avalanches in each mountain range and at every exposition. Some of them with run-outs like I've never seen before.

Everything has slid here.

Individual snow rafts seem to glide well into the flat parts with very little friction. They look more like mudslides.

Amazingly long run out (it continues well into the shadow)

Look at the crown on the one on the left. We estimated it at well over 5 m!

An avalanche with crevasses? That says something about how active the glaciers are.

Airborne surveys in Alaska

We spent a wonderful two weeks at Ultima Thule Lodge in the Wrangell St.Elias mountains. Our goal was to do airborne glacier surveys all over Alaska. We run LiDAR surveys to measure how glaciers change over time and radar surveys to measure how thick they are. The program did not start well. Interior Alaska experienced one of the coldest springs ever recorded and the mountain weather was not very conducive to flying. But by the second week it warmed up and the weather finally cleared. Within just a few days I got to see some amazing mountains. Sometimes I think that by now I've seen a lot of the mountains of Alaska, but this trip showed me (again), that there is still so much more to see and do. Below is a selection of somewhat random pictures; I took more pictures on this trip than on any previous field trip ...

The Root Glacier near McCarthy with the stairway ice fall in the background. This is one of the largest ice falls in the world.

Paul Claus's Single Otter

A medial moraine

The beautiful moraines of the Kaskawulsh Glacier in Kluane National Park

Mt. St.Elias, at over 5,400 m one of North America's tallest mountains. In the foreground Malaspina Glacier

The beautiful sand beach by Yakutat and Mt. Fairweather in the background.

The front of Hubbard Glacier, North America's longest tidewater glacier, and one of only a handful of advancing glaciers.

Looking almost 100 km down the Fairweather Fault (the extension of the San Andreas Fault). In the background is Mt. Fairweather.

Hubbard Glacier and Gilbert Point. The healthily advancing glacier is threatening to build an ice dam at this location. It has happened twice already, in 1986 and again in 2002.

The fronts of Logan and Chitina Glaciers

The alien landing site: A glacier sinkhole.

Mt. Logan is a massive mountain. It is just short of 6000 m high, and quite possibly the most massive mountain on Earth.

Hole in the Wall Glacier: This is an overflow of another advancing glacier: Taku Glacier in the Juneau Icefield. This glacier did not even exist 150 years ago!

Taku Glacier