HERTFORDSHIRE NATURAL HISTORY SOCIETY. XXXVH 



memhors listened to an address on the geology of the district by- 

 Mr. E. W. Lewis of Leighton Buzzard, author of a work on the 

 geology of that neighbourhood. 



Mr. Lewis said that it would be scarcely necessary to remind 

 his hearers that they were now on the Chalk, one of the members 

 of tlie Cretaceous series, another, the Gault, not being far oft', the 

 boundary between these two formations running in a north-easterly 

 and south-westerly direction past the villages of Pitstone and 

 Ivinghoe. Beyond this boundary, just this side of Cheddington 

 Station, an outlier of the Chalk formed a terraced hill — West End 

 Hill. jS'earer the present spot, on the farther side of the valley 

 just below, which was cut out of the Chalk, an escarpment of the 

 Upper Chalk might be seen, and beyond again, by Ivinghoe, the 

 Lower Chalk, with the Totternhoe Stone, a hard bed forming 

 the highest portion of the Chalk Marl, the lower ground beyond 

 being occupied by the softer beds of the Chalk Marl, followed by 

 the Gault and the Upper Greensand. The Chalk once extended 

 much beyond its present limits, as shown by outliers and beds of 

 gravel containing chalk-flints, which might be seen far to the north- 

 west. Eain and rivers, floods and frost, had removed a mass of 

 clay, sand, and chalk, of vast thickness and great extent. The 

 Chalk resisted denudation from its permeable nature rather than 

 its hardness, for a porous bed allowed water falling upon it as rain 

 to sink into and pass through it, thus dissolving it in an even 

 manner, and to this character the Dunstable Downs owed their 

 present form and the hills in all chalk-districts their gently-rounded 

 contours. The irregular outline of Totternhoe Knoll was not due to 

 denudation, but to the tumuli and earthworks upon it. 



After alluding to the former extensive use of the Totternhoe 

 Stone for building purposes, treating of the origin and composition 

 of the Chalk, and showing that its escarpment must have been 

 formed by subaerial and not marine denudation, Mr. Lewis 

 referred to the numerous springs at the foot of the Chalk escarp- 

 ment, due to the Totternhoe Stone arresting the flow of water in 

 the Chalk, the Ordnance Map showing that the little feeders of the 

 Ouse took their rise at the line of outcrop of the Totternhoe Stone. 



At the conclusion of this address, here but briefly reported, 

 many of the members ascended the Monument, and from the 

 summit, which commands a view of portions of six counties, some 

 of the geological features of the country pointed out by Mr. Lewis 

 were clearly seen. Moneybury Hill, with its Roman tumulus, 

 was also visited, and tea was then provided near the Monument by 

 Mr. Littleboy. In proposing to their host a vote of thanks, the 

 present writer remaiked tliat it was not the first or even the 

 second time that Mr. Littleboy had provided refreshments on similar 

 occasions. 



A descent was then made towards Aldbury, and Tring Station 

 was reached by a shorter route than that before taken. 



