Alaska – A Patchwork Place

Patchwork Alaska

Studying plate tectonics in Alaska is especially interesting because of Alaska’s history, both recent and long past.  Even our text refers over and over again to the Aleutians as an example of an island arc caused by the collision of two oceanic plates.  Elsewhere on this site you can find videos posted by previous students about the 1964 earthquake and on the formation of the Wrangell- St. Elias Mountains, which are great too.  I really wanted to find something showing the even earlier history of the state – how it formed from a bunch of shoved together terranes of diverse origin.  I am pretty sure that sometime in the past I saw an animation that showed these little chunks coming together to make up our state, but I couldn’t find it on the internet.  The closest I could find was this video on YouTube, which is a little hard to see, but would still be worth showing to the class as you talked them through it.  I also found this article from National Geographic, which talks about some of the fossil evidence for current theories about how Alaska came together.  I especially liked this sentence: “Fossils suggest that the rest of Alaska was formed from a patchwork of small land chunks, known as terranes, that collected against North America like flotsam during the Mesozoic and early Cenozoic eras, between 251 million and 60 million years ago.”  That article refers to limestone in Southeast Alaska and might work nicely in combination with this Alaska Science Forum article  about fossils and limestone in the Brooks Range.  Finally, I found the picture from the USGS that I posted here.  While most geology maps of the state have so much detail that they are overwhelming for students, this is simplified but still shows what a hodge-podge of pieces Alaska is.