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Crater Lake History

Crater Lake History. Built on older shield volcano Growth of Mt. Mazama composite volcano Glacial erosion (concurrent with volcanism) Explosion craters fill with domes Massive eruption of Mt. Mazama and subsequent caldera formation Resurgent volcanism in caldera. Redcloud Cliff.

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Crater Lake History

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  1. Crater Lake History • Built on older shield volcano • Growth of Mt. Mazama composite volcano • Glacial erosion (concurrent with volcanism) • Explosion craters fill with domes • Massive eruption of Mt. Mazama and subsequent caldera formation • Resurgent volcanism in caldera

  2. Redcloud Cliff Grouse Hill

  3. “Llao Rock” (dome filling Mazama explosion crater)

  4. Dome filling explosion crater of Mt St Helens

  5. Llao Rock close up

  6. Llao Rock again

  7. Crater Lake History • Built on older shield volcano • Growth of Mt. Mazama composite volcano • Glacial erosion • Explosion craters fill with domes • Massive eruption of Mt. Mazama and subsequent caldera formation • Resurgent volcanism in caldera

  8. “Devil’s Backbone” (radial andesite dike)

  9. “Devil’s Backbone” (andesite dike)

  10. Cone volume = 1/3 pi r2 h 1500 m 9 km

  11. Cone volume = 1/3 X 3.14 X 4500m2 X 1500m = 31,808,696,819m3= 32 km3 1500 m 9 km

  12. 32 km3

  13. Pumice Desert (Mt. Mazama’s handiwork)

  14. Lava bombs

  15. The Pinnacles (fumarole-altered pyroclastics)

  16. Crater Lake History • Built on older shield volcano • Growth of Mt. Mazama composite volcano • Glacial erosion (concurrent with volcanism) • Explosion craters fill with domes • Massive eruption of Mt. Mazama and subsequent caldera formation • Resurgent volcanism in caldera

  17. Gas depleted magma

  18. Merriam Cone Wizard Island Central Platform

  19. The only crater at Crater Lake

  20. Lake level now in equilibrium Porous layer

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