Agreed, but what I am getting at is trying to determine an absolute earliest possible start date. The pile cannot be older than the oldest object in it, so regardless of any other factors, you can at least determine X is the earliest possible start date, then you can use other details to reconstruct other pieces of data (aka the other objects in the pile)

obviously there will be a range of ages, but I'm just following the thread of the oldest object for a starting point, not as an absolute age for everything in the pile.