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Intro

Intro. How the formation of the Appalachian Mountains controlled the formation of the United States. Formation of the Apps. Formation of the Appalachians: Taconic Orogeny. Proto N. America. 1st island arc ‘docked’ against eastern North America. Formation of the Appalachians.

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Intro

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  1. Intro How the formation of the Appalachian Mountains controlled the formation of the United States

  2. Formation of the Apps Formation of the Appalachians: Taconic Orogeny Proto N. America 1st island arc ‘docked’ against eastern North America

  3. Formation of the Appalachians Acadia Orogeny (after Taconic) Alleghanian Orogeny: Final closure of ocean basin Taconic Orogeny (first)

  4. apps pangea Alignment of Appalachians and Caledonides during Pangea

  5. Pangea

  6. Initial doming & upwarping Pangea begins to break up, just east of the Appalachians

  7. Triple Junction A series of triple junctions form east of the Appalachians

  8. Rift Valley Appalachians over here somewhere Europe/Africa Future Atlantic Ocean North America

  9. Breakup of Pangea

  10. Linear rift valley Active rift zones of triple junctions align to form long rift valley Failed rift arms (aulacogens) form major continental drainages

  11. Aulacogen Lacustrine deposits at top Basalts & dikes at bottom

  12. East African Rift Zone Similar to aulacogen

  13. Linear sea Europe/Africa North America New Atlantic Ocean

  14. Mature mid-Atlantic ridge North America Europe/Africa Present-day Atlantic Ocean Widening of the Atlantic has taken about 200 million years. In the meantime, the Appalachians -- originally about 30,000 feet tall -- have been eroding…

  15. Continental Shelf … in the meantime Debris from weathering and erosion of Appalachian Mountains. Distributed downslope by mass wasting and streams/rivers. Starts here, not at the present-day location of the beach 10,000 - 15,000 feet thick

  16. Atlantic aulacogens

  17. NA aulacogens Failed rift basins (aulacogens) in North America Still seismically active (1906 Charleston ‘quake, numerous earthquakes in New York)

  18. mid-atlantic Hard rocks (folded & faulted continental shelf rocks - lots of marine fossils) Hard rocks (island arc rocks, all volcanic) Fall Line (escarpment separating volcanics from coastal plain sediments Coastal Plain (sediment)

  19. US topo Fall Line

  20. Columbia, SC Rapids Broad River

  21. New England 1.2Ga rocks (that’s billion years) Taconics (600 million years old) Acadian Rocks Major drainage systems are aulacogens

  22. putting it all together Putting it all together Coarse material Fine material Rock fall Rock slide Talus Stream transport -> Creep Debris flows Beach sand & sedimentation on continental shelf Fall Line Mechanical weathering Chemical weathering

  23. End Yes, these are the Appalachians…

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