River Mole Brook, Gatwick Stream, Earlswood Brook, Pipp Brook and The Rye, which drains Ashtead. A full list of the tributaries is given in the table below. River Mole The River Mole is a tributary of the River Thames in southern England. It rises in West Sussex near Horsham and flows northwest through Surrey for to the Thames at East Molesey, opposite Hampton Court Palace. The river gives its name to the Surrey district of Mole Valley. The Mole crosses the North Downs between Dorking and Leatherhead, where it cuts a steep-sided valley, known as the Mole Gap, through the chalk. Much
River Mole is thought to have merged with the River Wey near Byfleet and then flowed in a north-easterly direction via Richmond to meet the proto-Thames near Ware in Hertfordshire, (today the Mole and Wey are less than apart at their closest point near Painshill Park). During the Middle Pleistocene period, a large ice sheet built up across much of the East of England, reaching as far south as St Albans and Chelmsford, blocking the path of the proto-Thames. Glacial meltwater from the Anglian ice sheet, caused the Thames to divert southwards and flood the valley of the Mole–Wey river, thus adopting