The area north of the Middle Thames situated between Acton and West Drayton reveals extensive deposits which have been referred by H.M. Geological Survey to the Boyn Hill, Taplow, and Low terraces. As within the valley of the Lower Thames, these features have yielded implements and mammalian remains. In the opinion of the officers of the Geological Survey the formation of the Taplow terrace and its contained deposits occurred prior to the formation of the Coombe Rock which succeeded Early Mousterian times; further, they consider this Coombe Rock is to be equated with the ‘Trail’. It has long been established that the series of deposits revealed in a typical section cut through the so-called Taplow terrace of the Middle Thames in this district shows:
5. Surface soil.
4. ‘Trail’, often composed of slipped material from the Boyn Hill or ‘100-ft.’ terrace.
3. Brickearth, with thin layers of pebbles in its lower portion representing land-surfaces, overlying gravel with black seams.
2. Gravel, unstratified, much contorted, and containing large included masses both of solid Chalk and of London Clay.
1. Gravel, stratified, but showing a disturbed and deeply eroded upper surface penetrated by deposit no. 2.
Whereas deposits nos. 1, 2, and 3 have all been regarded as having been laid down by the river during the Taplow terrace stage, it would appear that this is not the case. There are reasons, archaeological and geological, for considering that these beds represent three separate periods and that only one of them (deposit no. 1) belongs to the Taplow terrace sequence proper.
It is the purpose of this article briefly to enumerate the facts which cause the correctness of the official geological reading of this type-section to be questioned.