List layers from youngest to oldest.

1. 3- Intrudes all

2. 1- Has only one intrusion and is the top layer

3. 6- Has only one intrusion and is the second highest labeled layer

4. 2- intrudes all layers but 1, 3, and 6 so it has to be younger than 5 and 4

5. 5- Second lowest layer

6. 4- Third lowest layer