1. 1. One half of the radioactive potassium-40 (K 40 ) in an igneous rock has decayed to argon-40 (Ar 40 ). According to the ESRT, about how many years ago was this rock formed? (1) 1.3 x 10 9 (2) 2.6 x 10 9 (3) 3.9 x 10 9 (4) 9.8 x 10 9 2. State one difference between dating with radioactive isotope Carbon-14 and dating with the radioactive isotope uranium-238. Carbon-14 can date organic remains. Uranium-238 has a longer half-life.

2. Volcanoes Famous Eruptions Volcanic debris Types of volcanoes and lavas Hazards and benefits of volcanoes

3. Lava Types Viscosity- a fluid’s resistance to flow. High viscosity-Low viscosity- Slow moving High silica content Fast moving Low silica content Rhyholitic (felsic) Basaltic (mafic)

4. Volatiles- trapped gasses and liquids in a molten material Increase explosiveness of a volcano

5. Stratovolcano (Composite volcano)

6. Mt. St. Helens http://www.classzone.com/books/earth_science/terc/content/investigations/es0907/es0907page03.cfm?chapter_no=investigation

7. May 17, 1980 Harry Glicken, USGSAugust 13, 2005 Valerie Smith Before and After the Eruption

8. Shield Volcano Mauna Loa, Hawaii

9. Cinder Cone Paricutin, Mexico

10. Caldera Crater Lake, Oregon

12. Pyroclastic debris- deposits of volcanic origin Volcanic debris Blocks- greater than 64 mm in diameter Lapilli- 2-64 mm in diameter Ash- less than 2 mm in diameter Bombs- greater than 64 mm in diameter (molten material) Tuff- rock composed of compacted fragments of volcanic origin

13. Nuée ardente- fast moving, glowing, cloud of gas and ash Volcanic debris http://www.geo.mtu.edu/volcanoes/hazards/primer/pyro.html

14. Volcanic debris Mudflow (aka: lahar)- the rapid downhill flow of a mixture or rock fragments, soil, and water. Can travel tens to hundreds of miles away from the volcano Associated with snow covered mountains Mt. Rainier (OR), Mt. St. Helens (WA) http://www.classzone.com/books/earth_science/terc/content/investigations/esu301/esu301page08.cfm?chapter_no=investigation

16. Volcanoes Around the Universe Io Large moon of Jupiter Similar size and density to Earth’s moon Most volcanically active body in our solar system

18. Mt. St. Helens Famous Eruptions: http://www.classzone.com/books/earth_science/terc/content/investigations/es0907/es0907page03.cfm?chapter_no=investigation

19. May 17, 1980 Harry Glicken, USGSAugust 13, 2005 Valerie Smith Before and After the Eruption

20. Mt. St. Helens Facts: It is a stratovolcano (or composite volcano), located in southwest Washington State. May 18th, 1980, 8:32 am (PDT). Eruption was triggered by a 5.1 earthquake centered beneath the mountain. The massive ash cloud grew to 80,000 feet (18 kilometers) in 15 minutes and reached the east coast in 3 days. Although most of the ash fell within 300 miles of the mountain, finer ash circled the earth in 15 days and may continue to stay in the atmosphere for many years. 57 people were killed as a result of the eruption. Of these, 21 bodies were never recovered from the blast zone.

21. Blow Down Forest 1981 2004 7,000 big game animals, 12 million Chinook and Coho salmon, and millions of birds and small mammals are believed to have died in the eruption.

22. Mt. St. Helens Eruption Picture From the Deck of Hoffstadt Bluffs Visitor Center Mount St. Helens Re-born - Oct. 4, 2004

23. Current Eruptions December 15, 2007 Popocatepetl, Mexico Giant plume of ash and steam spewed up to heights of 3,000 m (2 miles) Volcanic ash from a single eruption can be deposited in a thin layer on the ground worldwide. Ash deposits can help with relative age dating of rock strata.

24. Risks Associated with Volcanos Loss of land, livestock, homes (etc), trees Weather is affected by ash particles in air Injuries, deaths of humans

25. Benefits of Volcanoes Soil around volcanoes is rich with minerals for plants/crops. Geothermal heating of homes close to volcanic regions. Hot springs. Tourism.