David:  Since you asked, I'll weigh in on the question of NY as farmland.
Bear in mind these are the observations of an urban historian. It's my
impression that what makes "desirable famland" changes depending on the
farming practices being used.  So, like everything else, "desirable farmland"
is a historically contingent term.   In an article called, "Stone Age New
England: A Geology of Morals," Michael M. Bell argues that New England wasn't
such bad farmland after all.  I can't evaluate his claims as agricultural
history.  Yet, his claim that the myth of the rocky unproductive  soil serves
better to legitimize Manifest Destiny than to describe New England makes
sense.  And besides, I hear they grow pretty good grapes in the Finger Lakes.
 My vegetable garden isn't bad either come to think of it. --Jane Holzka