4 is the oldest because if you turn it to the side it's the furthest one down. Then 5 because its the next one up, than 5 becayse its the next one up. than 2 because it's an intrusion that only goes through 5 and 4. Then 6 because it's the next one up. Than one because it's the next one up, than 3 because it's an intrusion that goes through all of them.