Mount Saint Helen: Back from the DeadName:______

PBS Nova

This video shows a great example of PRIMARY SUCCESSION

  1. What is a pyroclastic flow?
  1. What area (how many square miles) were affected?
  1. What is the Pacific Ring of Fire?
  1. What did biologists want to know after the eruption?
  1. What was the first sign of living things?
  1. What signs make it look like the volcano might erupt again?
  1. What is the first sign of life on the pumice plain?
  1. What is special about the roots of prairie lupine?
  1. What special kind of species is the lupine?
  1. How long does the volcano continue to be active?
  1. What living things were left in the lake after the eruption?
  1. Why did most other living things die (fish, amphibians and insects)?
  1. After the debris settles and the water clears, what living things reappear in the lake?
  1. How did the gophers survive? (what food did they eat?)
  1. After plants become established, give two examples of other animals coming back?
  1. How do fish come back to SpiritLake?
  1. How fast could the lave dome grow?
  1. What gives volcanoes their explosive force?
  1. What determines if the lava will build spines or erupt in an explosion?
  1. When might the next big eruption come?

Mount Saint Helen: Back from the Dead

PBS Nova

This video shows a great example of PRIMARY SUCCESSION

Spring 1980: Mount Saint Helen is one of the major peaks in the Cascade Mountains

  1. What is a pyroclastic flow? A cloud of hot gas and steam
  2. What area (how many square miles) were affected? 200
  3. What is the Pacific Ring of Fire? An area where plates of the crust are being squeezed together, many volcanoes occur along the edges.
  4. What did biologists want to know after the eruption? Did any life survive
  5. What was the first sign of living things? Earth was dug up by burrowing Northern pocket gophers.
  6. What signs make it look like the volcano might erupt again? Ash and steam, and the dome keeps rising.

Spring 1981

  1. What is the first sign of life on the pumice plain? A prairie lupine (a purple flower)
  2. What is special about the roots of prairie lupine? It has bacteria that provide nitrogen fertilizer on the roots (We called these nitrogen-fixing bacteria in class!)
  3. What special kind of species is the lupine? A pioneering species
  4. How long does the volcano continue to be active? About 6 years
  5. What living things were left in the lake after the eruption? Bacteria
  6. Why did most other living things die (fish, amphibians and insects)? There was no oxygen.
  7. After the debris settles and the water clears, what living things reappear in the lake? Microscopic plants (phytoplankton)
  8. How did the gophers survive? (what food did they eat?) lupines
  9. After plants become established, give two examples of other animals coming back? Salamanders, amphibians (frogs) elk
  10. How do fish come back to SpiritLake? Fishermen bring them.
  11. How fast could the lave dome grow? Up to 16 feet each day
  12. What gives volcanoes their explosive force? Gas in the magma
  13. What determines if the lava will build spines or erupt in an explosion? The amount of gas
  14. When might the next big eruption come? Scientists can’t predict because there is no predictable pattern