The topography of the area is dominated by (a) a series of parallel, narrow, elongate ridges and intervening valleys that run N60E - S60W across the entire width of the central one-third of the region; and (b) the Susquehanna River, a mile-wide stream that flows in a curving path from the northern to the southern boundary of the map, cutting right across the mountains. Narrow streams that lack tributaries flow in fairly straight paths towards the Susquehanna along the bottoms of the valleys between the ridges.
The relief of the region is about 1250 feet: the highest parts of the ridges reach an elevation of more than 1600'; the banks of the Susquehanna are at about 350 feet above sea level.
The 'ridge and valley' region comprises four long, narrow mountains (ridges) separated from each other by three long, narrow valleys. Three of the ridges extend right across region. The remaining ridge tapers out to the southeast before it reaches the Susquehanna River. To the west of the Susquehanna, the two southernmost ridges depart slightly from the general NE-SW trend to head more directly due west. Three of the ridges have sharp crests; the ridge that tapers out has a fairly broad, flat top in its higher reaches. Where the Susquehanna cuts through the ridges, the truncated ridge slopes are quite steep, in places more than 30 degrees.
The southern one-third of the region is quite different on the two sides of the Susquehanna. To the east of the river, it is characterized by low, irregular, rolling hills that have a total relief of about a hundred feet. Elevations are generally between 400 to 500 feet. Streams with tributaries that branch and rebranch like the veins of a leaf flow seemingly randomly between the hills.
To the west of the river is a particularly interesting feature. A major stream flows along a path that consists of a series of looping, U-shaped segments. Most of the 'arms' of the 'U's are roughly parallel and run perpendicular to the trend of the ridges and valleys in the central part of the region. The arms of the 'U's are one to two miles long; the widths of the 'U's average less than a mile across. The U-shaped segments of the stream enclose and define elongate hills that rise as much as 140 feet above the banks of the stream. These hills do not occur outside the arms of the 'U's.
The northern third of the region has a poorly defined, lower, somewhat discontinous ridge parallel to those of the ridge and valley region. The ridge achieves elevations of 800 to 900 feet. It rises out of a region of low, rolling, hills and valleys whose total relief is about 200 feet, with elevations generally between 400 to 600 feet. Streams with tributaries that branch and rebranch flow between the hills.
The Susquehanna is an impressive river, in places a mile wide. Along its length are a series of swarms of low, narrow islands, elongate parallel to the shores. The path of the river seems unaffected by the nature of the land on either side: it slices through both mountains and low, rolling hills.
David J. Leveson