At Sea
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Endicott Arm (Wiki)
The Endicott Arm is a fjord in the Boundary Ranges in the U.S. state of Alaska , 80 km south of Juneau .
It is about 45 km long and 20% covered by ice. At the end of the fjord lies the Dawes Glacier . The fjord was named in 1889 by HB Mansfield after William Crowninshield Endicott , a Secretary of War under President Grover Cleveland .
The fjord is located in the Tongass National Forest on the Stephens Passage , a strait in the Alexander Archipelago , from which it runs in a southeasterly direction. In 1980, the Endicott Arm, together with the parallel Tracy Arm and their surroundings, totaling over 2640 km², were declared a Wilderness Area by the United States Congress under the name Tracy Arm-Fords Terror Wilderness , the most stringent class of nature reserves in the United States.
On the north shore of the Endicott Arm, the long, narrow side bay of Fords Terror branches off.
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Dawes Glacier
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The ridges on the rock left behind after a glacier recedes are called glacial striations. These striations are formed by the movement of the glacier over the bedrock. As the glacier moves, it carries with it rocks and debris that are embedded in the ice. These rocks act like tools that scrape and gouge the surface of the underlying bedrock, creating grooves or ridges.
The process occurs in the following steps:
Plucking: Glaciers can pick up rocks and debris from the ground. This process, called plucking, involves the freezing of meltwater in cracks and joints of the rock. When the glacier moves, it pulls chunks of rock away.
Abrasion: The debris and rocks embedded in the glacier?s base grind against the bedrock beneath as the glacier moves. This action is similar to sandpaper rubbing on wood, and it creates long, parallel scratches or grooves called striations.
Direction of Movement: The orientation of these striations can indicate the direction of the glacier’s movement. The striations are typically aligned with the flow direction of the glacier.
These striations and other features left behind by glaciers, such as roche moutonnées and chatter marks, provide valuable information about the history of glacial movement and the nature of the bedrock over which the glacier traveled.
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The growth of plants along horizontal ridges in a glacial region in Alaska can be explained by several factors related to the unique environmental conditions created by glacial activity. Here are some potential reasons:
Moraines: As glaciers advance and retreat, they deposit moraines, which are ridges of till (a mixture of soil and rock). These moraines can create elevated areas that are better drained than the surrounding terrain, making them more suitable for plant growth.
Exposure and Sunlight: Horizontal ridges may be more exposed to sunlight compared to the surrounding valleys or depressions. Increased sunlight can promote plant growth, especially in cold, glacial regions where warmth and light are limited.
Soil Development: Over time, moraines and other glacial deposits can develop a thin layer of soil as organic matter accumulates and weathering processes break down the rocks and minerals. This developing soil can provide a suitable substrate for plants to take root and grow.
Water Drainage: Ridges can provide better drainage than flat or depressed areas, preventing waterlogging and creating conditions more favorable for plant growth. Well-drained soil is essential for many plant species, as it allows for better root development and reduces the risk of root rot.
Microclimates: The ridges may create microclimates that are slightly warmer or less prone to frost compared to lower-lying areas. These microclimates can support a different or more diverse plant community.
Reduced Competition: Initially, newly exposed glacial areas may have less competition from established plants. This can allow pioneering species to colonize and establish themselves more easily on the ridges.
These factors combined can create an environment along the horizontal ridges that is more conducive to plant growth compared to the surrounding areas. As a result, you might observe more vegetation in these specific locations.
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Too many shades of gray to count, but the crack in the heavens lets the light in, and gives some hope for a new and better dayEndicott Passage Alaska
Acknowledging the Free Museums In And Around Us