Unit 3 Ice Ages

2. all of the fossils that have ever been found, which scientists use to understand Earth's history
4. the conditions of the atmosphere (temperature, humidity, wind speed, and precipitation) at a particular place and time
8. the eroded sediment that is deposited as glaciers retreat and expand
11. a global climate marked by long periods of cold temperatures that cause glacial formation and expansion
12. certain fossils known to exist in a particular time and place that may be used to determine the age of rocks or other fossils
13. the circulation of water through the hydrosphere from Earth's surface to the atmosphere and back
14. the transport of sediment by wind, water, or gravity

1. when a species no longer has living members in existence
2. the remains of ancient animals and plants, the traces or impressions of living things from past geologic ages, or the traces of their activities
3. periods of time characterized by specific weather patterns and the length of day and night
5. the comparison of fossils in different rock layers to determine how old a rock or fossil is
6. a flowing mass of ice and snow that forms on mountaintops and near the North and South poles
7. the average weather in a location over 30 years or more
9. cylinders of ice drilled out of glaciers that contain layers of snow, dust, volcanic ash, atmospheric gases, and microbes from past time periods
10. the breakdown of rock into smaller pieces from exposure to wind water gravity, changes in temperature, and/or biological forces