'Sharp differentiation'

“In New England we have but to step across the border of the adjoining state to feel at once the sharp differentiation, the geological cut-off which expresses itself in the general aspect of the land and in the thousand and one simple facts of its topography, its flora, its fauna, its people, its customs, its coast, its climate, and its industries.’’

— Helen Henderson, in A Loiterer in New England (published in 1919)