Read it through once

Where the great rivers Thames, Humber, Tyne, Forth, Clyde, Mersey, and Severn, approached the seashore they lost themselves in wildernesses of desolate, dreary fenlands. Here a small scrubby wood of willow, birch, and alder; there a miles-wide stretch of reeds and undrained marsh intersected by sluggish, lazy rivers, or varied by stagnant pools. The bittern boomed in those marshes. Herons, geese, swans, ducks, and aquatic birds of all sorts found what is now Chelsea a paradise, only disturbed by the eagle, harrier-hawk, vulture, and the like.