Geology of the Boulder Area

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Across
  1. 5. Deposited along an ancient sea shore 100 million years ago
  2. 8. Glaciers and running water carved the topography and left behind huge boulders
  3. 9. Sandstone and conglomerate deposited about 280-300 million years ago
  4. 10. Deposited at the bottom of the Cretaceous Western Interior Seaway
Down
  1. 1. Formed about 270 million years ago from desert sand dunes
  2. 2. Formed when the North American Plate collided with South America
  3. 3. Caused the Rocky Mountains to be uplifted as the Farallon Plate subducted between the North American plate
  4. 4. Magma cooled deep understory to form the Boulder Creek Granodiorite
  5. 6. Left behind layers of Pierre Shale and Dakota Sandstone
  6. 7. Igneous rocks that formed at the core of the mountains and slowly moved upwards and cooled