Wooldridge SW, Linton DL (1955), Structure, surface and drainage in South-East England. Philip, London, Chapter VIII (vi). (But the suggestion there that Thames itself, after passing over gaps south of Watford, then flowed north-east through the "Finchley depression" is not now accepted.)
bgs.ac.uk
geologyviewer.bgs.ac.uk
See BGS Geology Viewer (British Geological Survey) for more information on the distribution of all the formations mentioned in this section.
