Alaska Time Zone to 1967 refer to this zone as Central Alaska Standard Time (CAT) or as Alaska Standard Time (AST). In 1966, the Uniform Time Act renamed the UTC−10 zone to Alaska-Hawaii Standard Time (AHST), effective April 1, 1967. This zone was renamed in 1983 to Hawaii-Aleutian Standard Time when the majority of Alaska was moved out of the zone. Prior to 1983, the current Alaska Time Zone (UTC−9) was known as the Yukon Time Zone, observing Yukon Standard Time (YST). This time zone included Canada's Yukon Territory and a small portion of Alaska including Yakutat. The Alaska Panhandle communities were in
Geology of the United States streams downcut so rapidly that they cut right across the resistant folded rocks of the mountain core, carving canyons across rock layers and geologic structures. Most of Alaska consists of terranes accreted by collisions with island arcs carried in over the last 160 million years. These terranes were caused by the subduction of the Farallon, Kula, and Pacific plates sequentially. Currently, the Pacific plate is subducting beneath Alaska, producing the Aleutian arc series of volcanoes through the Alaskan Peninsula and Aleutian Islands. One of the sutures left by terrane addition is the Denali Fault, which curves through south-central Alaska. The