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Rock Doc: Alaska’s coastal glaciers have much to tell

Mon., July 15, 2013

Each year at this time, thousands of tourists embark on cruises along Alaska’s stunning coastal waters.

If they are lucky, the tourists experience dry weather, relatively calm seas and breathtaking vistas. In some places, the ships can get close to dramatic scenes of glaciers calving ice as it breaks off and falls into the ocean. Although I’ve hiked up to glaciers in the Rockies and walked across them, I’ve never seen them entering the sea. I’d like to do that and have the notion recorded on my “bucket list” of things left to do before I die.

The landscape visible to cruising tourists each summer is actually quite dynamic. If we could go back in time several hundred thousand years, the Alaska coast would be a bit different than it is today. Glaciers do their work slowly by human standards, but over geologic time scales they impact whole landscapes.

This summer a scientific research vessel is plying the Alaska waters along with the ships carrying tourists. The JOIDES Resolution is an ocean drilling vessel that will study glaciers and their effects on mountain-building processes. The ship left Victoria, B.C., in late May and will finish its work at the end of July. It will sample sediments from five places around the Gulf of Alaska. The plan is to study long-term climate change, the influence of such change on major glaciers and the glaciers’ impact on mountain-building processes.

As we’ve known since around 1840, glaciers can move large amounts of rock and thus shape whole landscapes. The man who first really understood this effect was Louis Agassiz, who studied alpine “rivers of ice” in Switzerland.

Today we know that because they remove large quantities of rock from whole regions, glaciers can trigger uplift on geologically fast time scales (on the order of a million years or less).

“Mountains grow when numerous faults thrust layers of rock on top of each other,” said Sean Gulick of the University of Texas at Austin in a National Science Foundation news release. “We’re asking whether this increases in locations with lots of erosion, such as beneath Alaska’s glaciers.”

Southern Alaska is a perfect place to study because of its large glaciers and rapidly rising mountains.

Some scientists aboard the research vessel will study ocean floor sediment to look at changes in ocean circulation patterns over time. Such circulation may affect the carbon cycle of our planet as the Earth experiences repeated ice ages punctuated by warmer times.

Modern scientific research is often a complex business, involving teams of researchers, complex laboratory equipment and sometimes even ocean-going drilling vessels like the JOIDES Resolution. But through such research we are learning a great deal about the history of our planet and how climate, glaciation and mountain- building processes are intertwined.

Now if only I could figure out how to get a berth on board a research ship headed to Alaska’s stunning coastal waters.

Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard universities. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.

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