Yukon Time Zone clocks ahead yet another hour on October 30, 1983 to adopt Alaska Standard Time (the former Yukon Standard Time), effectively changing their standard time zone by two hours. Most of the Aleutian Islands moved from the Bering Time Zone (UTC-11) to the Hawaii-Aleutian Standard Time Zone (UTC-10) (until 1983 known as the Alaska-Hawaii Standard Time Zone). Yukon Time Zone The Yukon Time Zone was a time zone that kept standard time; Yukon Standard Time (YST) was obtained by subtracting nine hours from Coordinated Universal Time (UTC) resulting in UTC−9. Yukon Daylight Time (YDT) when observed was eight hours behind UTC.
Aleutian subduction zone rocks, with trace amounts of Paleozoic rocks intruded by Mesozoic batholiths. Most of the Aleutian Islands are composed of sedimentary rocks from granitic and metamorphic rocks from Oligocene-Miocene. There are Quaternary volcanoes on the north of the Aleutian Islands structural axis, which is composed of andesite mostly, mixed with olivine basalt to rhyolite. The eastern Aleutian volcanoes have more silicic magma while the western Aleutian arcs lack the sial magma. The Aleutian Trench formation is associated with the subduction of the Pacific Plate beneath the North American plate. The horizontally-curved shape of the trench is due to the change in