How often does the Earth have an ice age?

Related questions

1. What are the 5 major ice ages?
2. What era are we now?
3. How much of the Earth was covered in the last ice age?
4. What caused the last ice age to end?
5. How did humans survive during the ice age?
6. Can an ice age happen again?
7. Can a volcano cause an ice age?
8. Did humans live in the Pleistocene?
9. Do humans share 50 DNA with bananas?
10. How old is the human race?

Tags

1. #frequently
2. #sheets
3. #periods
4. #glacial
5. #quaternary
6. #glaciation
7. #these
8. #sandstrom
9. #during
10. #appeared
11. #every
12. #million
13. #beginning
14. #about
15. #occurred
16. #however
17. #years