| Summary: | The Gulf of Alaska domain extends eastward from Kodiak Island across the Kenai Peninsula, around the Chugach Mountains, and beyond Tonsina, curves southward across the glacier-covered St. Elias Mountains. The southeastern segment of the domain is west of the Canadian Coastal Mountains and includes the coastline and islands in southeastern Alaska. Ultramafic rocks occur sporadically in this region from British Columbia northwestward through southeastern Alaska and around the Gulf of Alaska to the Kenai Peninsula. Most of this domain is mountainous, especially in areas where there are ultramafic rocks. Elevations range from sea level to >5000 m, although ultramafic rocks are not found at the highest elevations. This area was glaciated during the Pleistocene. Many glaciers persist at the higher elevations, and some descend to sea level. The present climate ranges from cold to very cold and from humid to very humid, or perhumid. Mean annual precipitation ranges from 30 or 40 cm on the north side and west end of the Chugach Mountains, to >400 cm along the coast around Prince William Sound and in southeastern Alaska. Southeastern Alaska is a humid-to-perhumid area with dense forests at lower elevations that grade upward into alpine areas. The north side of the Chugach Mountains is drier, but still humid. Precipitation exceeds evapotranspiration in all months of every year. The frost-free period ranges from no more than a few days or weeks at the higher elevations to about 220 days in sheltered areas near sea level in southeasern Alaska. Some of the highest snowfall in North America is in this domain, and ice caps persist in some of the higher mountains with many glaciers flowing into the sea. Serpentine rocks of the Gulf of Alaska domain occur in both ophiolites and in concentric bodies, and some are from the roots of volcanic arcs complexes. West of the Chatham Straight fault, a discontinuous belt of ultramafic bodies extends for >1600 km from Kodiak Island across the Kenai Peninsula, and around ...
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