Prior to the Anglian glaciation, a "proto-Mole-Wey" river was flowing northwards from the Weald and North Downs, through the "Finchley depression" and Palmers Green, to join the proto-Thames somewhere around Hoddesdon, at what is today an altitude of around 60 metres.
Before the Anglian glaciation, a precursor to the Mole-Wey river flowed northward from the Weald and North Downs through the Finchley depression and Palmers Green, where it joined a predecessor of the Thames River near Hoddesdon, currently at an elevation of around 60 meters.