It is a typical Lake District narrow `` ribbon lake '' formed after the last ice age when a glacier scooped out the valley floor and when the glacier retreated , the deepened section filled with meltwater which became a lake .
It is a typical Lake District narrow `` ribbon lake '' formed after the last ice age when a glacier scooped out the valley floor . When the glacier retreated , the deepened section became a lake.Three separate glaciers formed the lake .