Perhaps the Oaks don't grow up there because that area is an ancient glaciated region with poor soils for the most part. As a matter of fact, there is no real soil there. Just sandstone (river rock) in various sizes from sand to giant boulders. Just try digging a ditch up that way sometime. You'll have very soft sand for a ways and then you hit a boulder the size of a car, then some more sand. Oaks like fairly moist soil conditions. Hard to keep wet when water runs straight thru sand like it does. Just guessing here.