1. Geologic History Of Washington State
... "homeland." This was the dominant landmass of Earth for nearly 350 million years. Western North America used to lie next to what is now Australia and Antarctica. This world was a dark and hostile one, where the only life to exist was probably single-celled organisms. Oxygen in the atmosphere was only 5% of what it is today, and was lacking the protective ozone layer to ... shield it from harmful radiation. These are the conditions in which Washington formed under more than a billion ... these changes that may have contributed to a mass extinction where near 90% of all species were elim...
- Word Count: 1275
- Approx Pages: 5
- Grade Level: High School