Arrange the following major discoveries of natural resources chronologically:
- North Sea Oil (Europe)
- Shale Gas (United States)
- Diamond mines (Botswana)
- Tar Sands (Canada)
1
4 - 2 - 3 - 1
2
1 - 4 - 3 - 2
3
1 - 3 - 4 - 2
4
3 - 1 - 4 - 2
Arrange the following major discoveries of natural resources chronologically: