Rain falls on the North Downs, filters through the chalk and emerges on the spring line at the Wandle's two main sources, both at about 115 ft (38 yd, 35 m) above sea level.
Rain falls on the North Downs. Rain filters through the chalk. Rain emerges on the spring line at the Wandle's two main sources, both at about 115 ft (38 yd) above sea level.38 yd is 35 m.