Alaska Time Zone to 03:00 LDT on the second Sunday in March and returns at 02:00 LDT to 01:00 LST on the first Sunday in November. Two time zones have been referred to as the "Alaska Time Zone": a zone based on UTC−10 that covered much of Central Alaska in the early 20th century, and a zone based on UTC−9 zone that has covered all of the state except the Aleutian Islands since 1983. The Standard Time Act of 1918 authorized the Interstate Commerce Commission to define each time zone. The United States Standard Alaska Time was designated as UTC−10. Some references prior
Aleutian subduction zone andesite, while the middle crust is composed of 5 km-thick mid-ocean ridge basalt (MORB), and 19 km- thick tholeiitic residue in the lower crust. Continental crusts usually have silicic upper crust and reflective lower crust, but these features are not found in the Aleutian arc. There are 40 active volcanoes in the Aleutian volcanic arc from the Mt. Spurr in mainland Alaska to Buldir Island in the far west Aleutian islands. The list of volcanoes in the Aleutian Arc could be found here. The eastern end of the volcanic arc on the Alaska Peninsula lies on Mesozoic sedimentary and volcanic