#Fold mountains
Don,
>> My problem is with the Applachians as a product of the Alleghenian orogeny.
It's clear that the mountains are post Pennsylvanian and pre-Cretaceous. <<
Is it? Sure, it's clear they have to be younger than the Pennsylvanian
sediments that are incorporated into the folds and faults. But do they have to
be 'pre-Cretaceous'?
JSW