I know that strategic resources are created when the map is initially created. What I'm wondering is if I start clearing forests, jungles and marshland before I discover the required technologies, will they still be there after I discover them? I'm playing a new game and I'm still in the ancient age. What I'm worried about is if I start clearing the forests, jungles and marshland in my territories, the resources that are supposed to be in my territory might be gone.