The Trinity Alps are a mountain range in Trinity County and Siskiyou County in Northern California. They are a subrange of the Klamath Mountains located to the north of Weaverville. Geography The Trinity Alps are within the Pacific Coast Ranges physiographic region, in the Klamath Mountains System, which lies between the California Coast Ranges to the west and the Cascade Range to the east. Elevations range from to on Thompson Peak. Other notable peaks include Granite Peak () and Ycatapom Peak (). The Trinity Alps are noted for their scenic views and alpine environment. The range's alpine flora differs from that found in the Sierra Nevada or the Cascades. Within the Klamath Mountains, adjacent subranges of the Trinity Alps include the Salmon Mountains and Scott Mountains. The Trinity Alps Wilderness covers , making it the second largest wilderness area in California. The area was formerly known as the Salmon-Trinity Alps Primitive Area since 1932 until a series of expansions. Glaciers, snowfields, and ice fields The lowest snowfield in California that does not disappear except in the extreme runs of dry years is located above Mirror Lake at an elevation of . The only unambiguous glacier is the Grizzly Glacier, a icefield on the north side of Thompson Peak, which shows crevasses indicating true motion even on so small an icefield. Research has shown that some glaciers in the Trinity Alps are more resistant to the effects of global warming than are other California glaciers. According to recent, but incorrect, USGS maps, 35 permanent bodies of snow and several tiny glaciers dot the highest peaks of the Alps. Temporary glacier On the ridge south of Sapphire Lake is an unusual phenomenon consisting of a temporary glacier, versus an inactive snowfield that melts out in dry years. Following years of heavy accumulation, an icefield appears in this fully sheltered north-facing cirque that can show active crevasses and seracs some tens of feet high. But this ice body, at an elevation of only in a region experiencing a long, hot dry season from about mid May to mid October, can disappear completely during a run of drier years. Studies of lichen collars indicate that the site near Kalmia Lake is the snowiest spot in the State of California, receiving snow accumulation in excess of the Lake Helen snowcourse on Lassen Peak, by far the snowcourse with greatest late winter snow accumulation in California.