Find all documents that are created more than four years old (based on created date)

Hi,

I am looking to write a Powershell script that can do the following:

1. Find all documents that are created more than four years old (based on created date)
2. For each of these document sets, find the oldest docuemnt (even if in a subfolder), and if the oldest document has not been modified in four years then set the document set metadata 'Ready to Archive' to 'Yes'.

The script should be running against a site collection and all webs within that Site Collection.

Thanks,

AB