A pinnacle of chalk penetrating the Eocene on the floor of a buried river-channel at Ashford Hill, Near Newbury, Berkshire

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Abstract
Summary: An isolated pinnacle of chalk,about 175 feet across and at least 150 feet above its normal level,rises through the Reading Beds and part of the London Clay near Ashford hill, and is associated with a drift-filled channel whose floor is, at its deepest proved point, 90 feet below the present ground-level. The channel reaches its greatest depth on the top of the chalk pinnacle, and seems not to extend beyond it. It is filled mostly with peaty silts with subordinate beds of gravel; and at depths of about 40 feet from the surface the pollen-content of the peats indicates a Lateglacial age. At the deepest point, almost 50 feet of alternating varves and Coombe Rock underlie the Late-glacial drift, in what appears to have been a swallow-hole. The pinnacle of chalk into which this pit was excavated has evidently been driven up through the Eocene when in a plastic state; its elevation and exposure must have antedated the development of the deep channel which apparently ends at it. In an attempted explanation of these associated anomalies (both of which seem to have developed during the Glacial Period) it is suggested that the chalk at the point of convergence of two faults may have been subjected to deep freezing and subsequently to "eruption" as a tectonically localized "valley bulge".

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