English: Sketch map showing the supposed approximate courses of the Ancestral (or Proto) Thames, and of other possible rivers (Proto Kennett, Proto Mole-Wey, Proto Darent, Proto Medway), in the Early Pleistocene epoch, around 1.5 million years ago.

The current coastline, and the current course of the River Thames, are shown in the background. Also shown is an area where "Pebble Gravel" deposits are found, north of today's Thames, notably at Harrow Weald Common, High Beach, Warley and Langdon Hills.
Sources:
- Bridgland, D.R. (1994, 2012), Quaternary of the Thames, Geological Conservation Review Series, Springer Science & Business Media, ISBN 978-94-010-4303-8, ISBN 978-94-011-0705-1 (eBook) (originally published by Chapman and Hall). Chapter 1.
- Bridgland D.R. and Gibbard P.L, 1997, Quaternary River Diversions in the London Basin and the Eastern English Channel, Géographie physique et Quaternaire, vol. 51, n° 3, 1997, p. 337-346.

- Rose, J., Whiteman, C.A., Allen, P., Kemp, R.A., 1999, The Kesgrave Sands and Gravels: 'pre-glacial' Quaternary deposits of the River Thames in East Anglia and the Thames valley, Proceedings of the Geologists' Association 110, page 99.