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Scientists are finding that glaciers reveal clues to the following questions about global warming.
How much does our atmosphere naturally warm up between Ice Ages?
How does human activity affect climate?
Because glaciers are so sensitive to temperature fluctuations accompanying climate change, direct glacier observation may help answer these questions. Since the early twentieth century, with few exceptions, glaciers around the world have been retreating at unprecedented rates. Some scientists attribute this massive glacial retreat to the Industrial Revolution, which began around 1760. In fact, several ice caps, glaciers and ice shelves have disappeared altogether in this century. Many more are retreating so rapidly that they may vanish within a matter of decades. Spencer Glacier is no exception.
When a glacier retreats, rock material is deposited as a mantle of debris covering the landscape. These areas of deposits are called moraines. These moraines are based on their location around the glacier: end, lateral, ground, recessional or terminal moraines.
Using the information boards at the overlook and your observations, please email me the answers to the following questions.
1. Between 1890 and 1990, Spencer glacier retreated an average of __ ft year.
2. Between 1990 and 2007, the glacier retreated and average of __ ft year.
3. Name four tools that scientists use to measure the movement of a glacier.
4. Based on your observation of Spencer Glacier, what type of glacial moraine is most notable from your vantage point at the overlook?
Photographs are not mandatory, but very much appreciated.
The above information was compiled from the following sources:
L.M. Dilley & T. Dilley, "Guidebook to Geology of Anchorage, Alaska", 2000 (1st edition) Anchorage, AK
USGS Bulletin, Glacier Climate Studies in Washington and Alaska, Briefing to the DOI Climate Change Workshop, August 2007