About Lamplugh Glacier:
Lamplugh Glacier is 0.9 miles wide, 165 feet high, and over 19 miles long. It has an intense blue color due to its ice. Lamplugh is fed by the Brady Icefield, which lies east of the Fairweather Range. As temperatures warm, and snow levels rise, the Brady Icefield accumulation areas appear to be shrinking yearly. A large subglacial stream flows from the central part of the terminus, often creating large caves in the face of the glacier. Such subglacial streams discharge large volumes of sediment-rich water into the fjord, filling the small embayment at the ice edge with brown to tan milky water. Since 2010, outwash has built up extensive mudflats along the entire face of the glacier. In 2015, a massive landslide dropped approximately 120 million metric tons of rock onto the glacier. The weight of rock altered the "internal plumbing" of meltwater within the glacier, impacting ice flow. The flow of ice still carries the burden of rock down to sea level, where the debris will be deposited.
Figure 1: Before and After Lamplugh Glacier’s landslide
What is a Tidewater Glacier?
Tidewater glaciers are types of glaciers that flow all the way down to the ocean. They often calve numerous small icebergs. The diagram belove illustrates the anatomy of this type of glacier.
Figure 2: Glacier diagram
Valley Glaciers vs. Mountain Glaciers
Valley glaciers- these glaciers commonly originate from mountain glaciers or icefields. These glaciers spill down valleys, looking much like giant tongues. Valley glaciers may be very long, often flowing down beyond the snow line, sometimes reaching sea level.
Mountain glaciers-Â these glaciers develop in high mountainous regions, often flowing out of icefields that span several peaks or even a mountain range. The largest mountain glaciers are found in Arctic Canada, Alaska, the Andes in South America, and the Himalayas in Asia.
Advancing and Retreating:
Glaciers retreat when their terminus does not extend as far downvalley as it previously did. Glaciers may retreat when their ice melts or ablates more quickly than snowfall can accumulate and form new glacial ice. Higher temperatures and less snowfall have been causing many glaciers worldwide to retreat recently.
Glacier advancement is when a glacier's terminus (mouth of the glacier) extends farther downvalley than before; glacial advance occurs when a glacier flows downvalley faster than the rate of ablation at its terminus.
Glaciers periodically retreat or advance, depending on the amount of snow accumulation, evaporation, or melting. This retreat and advance refer only to the position of the terminus, or snout, of the glacier. Even as it retreats, the glacier still deforms and moves downslope, like a conveyor belt. For most glaciers, retreating and advancing are very slow occurrences, requiring years or decades to have a significant effect. However, movement may be visible over a few months or years when glaciers retreat rapidly. For instance, a massive glacier retreat has been recorded in Glacier Bay, Alaska. Glaciers that once terminated in the ocean have now receded onto land, retreating far up valleys. Over the past several decades, scientists and researchers have begun to capture data and photographic evidence of this recession over time.
Logging Requirements:
- Is Lamplugh Glacier considered to be a valley glacier or a mountain glacier? Provide some evidence for your answer.
- Based on your observations at the GZ and what you’ve learned in the description, is Lamplugh Glacier a tidewater glacier? Why or why not? Does it seem to be retreating or advancing?
- Examine the appearance of this glacier. Record what you see at the GZ. How has the landslide that occurred in 2016 affected how Lamplugh Glacier looks?
- As of June 2019, earthcaches now contain required photo logging tasks. Please provide a photo of yourself, your GPSr, or a personal item that proves that you have visited this site. Please post this in your log.
**All observations and logging tasks should be completed looking at the glacier from your cruise ship or respective watercraft**
Sources:
https://nsidc.org/cryosphere/glaciers/gallery/retreating.html
https://www.nps.gov/glba/learn/nature/overview-of-selected-glaciers-in-glacier-bay.htm
https://nsidc.org/cryosphere/glaciers/questions/move.html
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