A swampy pass occurs midway of its length at an altitude of 120 feet ( 37 m ) .
A stream terrace lies on the eastern side of the valley near the pass , at an altitude of 150 feet ( 46 m ) .
A swampy pass occurs midway of its length at an altitude of 120 feet ( 37 m ) , and a stream terrace lies on the eastern side of the valley near the pass , at an altitude of 150 feet ( 46 m ) .