Lecture#26 12/1/08 Describe the geology and features of Voyageurs National Park Name refers to the French fur trappers Northeastern Minnesota Consists of a series of interconnected lakes, dotted with islands Geology: metamorphic rocks older than 2.5 billion years-known b/c intrusions of granite are exposed at surface with an age of 2.5 billion years old. Describe the geology and features of Isle Royale National Park. Largest island in Lake Superior Elongated islands were formed from glaciers Geology: Precambrian rocks (younger than rocks from Voyageurs NP), mostly volcanic basalt mixed with conglomerate and copper (1.5 billion years old) Define orogeny. Mountain building events Describe the plate tectonic history of the Appalachian Mountains making note of the nature and timing of the: Taconic orogeny; Acadian orogeny; Alleghenian orogeny. Taconic Orogeny : subduction zone (continental-oceanic) forming intermediate rocks (andesite), Proto Atlantic Ocean Craton subducted under N. American
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Orogeny, Proto Atlantic Ocean Craton, NA Craton, Proto Atlantic Craton, Atlantic Ocean Craton, African Craton