Quiz 3 already??!

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Across
  1. 2. One of the principles of relative dating that says the oldest rocks are on the bottom
  2. 5. Large boulder left behind when glaciers retreated
  3. 6. Time required for half of the nuclei of an isotope to decay
  4. 10. Scratch in rock caused by abrasion from glaciers
  5. 11. A break in time between different layers of sedimentary rock that resembles a bedding plane
  6. 12. Characteristic shape of valley formed by streams
  7. 14. Egg shaped hill formed when ice reworks till
  8. 16. Granular compacted snow
  9. 18. Moraine deposits at the furthest extent of a glacier
  10. 19. Ice core formed over a drained lake
  11. 21. Unsorted debris deposited directly by a glacier
  12. 23. Permafrost formation that forms network of troughs and polygons (2 words)
Down
  1. 1. Represents a break in time
  2. 3. Part of permafrost that thaws (and refreezes) annually (2 words)
  3. 4. Mound of till deposited at the end and sides of glaciers
  4. 7. Elements that have different atomic masses (pl.)
  5. 8. Zone of glacier where ice is lost by melting and evaporation
  6. 9. Subsidence of huge areas of land due to permafrost melting (3 words)
  7. 13. organisms believed to be responsible for oxygenating our atmosphere (pl.)
  8. 15. Unconformity between igneous or metamorphic rock and sedimentary
  9. 17. Fracture in crust along which appreciable displacement has taken place
  10. 18. Area that remains unfrozen under a lake
  11. 20. Long winding ridge of stratified sand and gravel to due movement of water through tunnels in the ice
  12. 22. the current geological era, which began 65 million years ago