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Alaska Peninsula Mountains

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About the Alaska Peninsula Mountains

The Alaska Peninsula Mountains are a mountainous region along the south side of the Alaska Peninsula, also called the Aleutian Peninsula, also extending onto Unimak Island, the first and largest of the Aleutian islands, and some other islands to the east including Kodiak Island.

The climate here is heavily shaped by the presence of the Aleutian Low, which both generates and strengthens storms, and attracts storm systems to this area; the low weakens or dissipates in summer. This region's climate straddles the border of most classification schemes, usually being classified as towards the cold end of an oceanic or maritime climate, but tending towards subarctic at mid elevations and tundra at high elevations, and with some small regions of cold-summer Mediterranean climate on the northwestern side of mountains. Temperatures are moderate year-round, having only a weak seasonality, with winter temperatures only about 25°F (14°C) lower than summer. Rainfall in most of the region is extraordinarily high, and although high year-round, is slightly lower in early summer. Winter snowfall is heavy, but accumulation is minimal at sea level because winter highs reach well above freezing on most days; at higher elevations, higher snowfall and colder temperatures can lead to great snow accumulation. An exception to the high precipitation pattern is on the lower, northwestern slopes of larger mountains, where rain shadow produces small areas with a dramatically drier climate; the largest such area occurs around Larsen Bay on Kodiak Island.

This area is rugged, with elevations spanning from 2,600m (over 8,500 ft) to sea level. Much of the mountains consist of folded and faulted sedimentary ridges, but there are also volcanoes reaching to much higher elevations. The terrain has been heavily glaciated, and some glaciers remain at the highest elevations. The shape of the terrain is different in areas bordering flatter land vs. water. Along the ocean, particularly on the south side, there are deeply-cut fjords. The north side of the mountains tends to be smoother and marked by glacial moraines. Soils here are mostly formed on volcanic ash and cinder, which lies atop glacial deposits; these soils are prone to erosion. Excluding the highest elevations covered in glaciers, most of this region is free of permafrost.

This area is mostly covered in low-growing scrub plant communities. Low elevations and more sheltered sites support willow, birch, and alder, with ericaceous plants, Dryas