47 



caused considerable deviation from their normal dip, and which 

 may have led to the formation of the Wardington Bottom by 

 determining the outflow of the springs ^ The combe is certainly 

 of very ancient date, so old indeed, as we shall presently see, 

 that all the rest of the valley into which it originally led has 

 been swept away by post-glacial denudation. 



At the head of this valley, about one mile and a half east of 

 Barley Church, is a small gravelly patch, but no exposure is 

 now to be seen in it. Lower down there is a larger jDatch 

 which sends a prolongation up the hollow towards Burloes Hill, 

 and about half a mile S.W. of Known's Folly there is a gravel 

 pit exposing — 



Chalky sand (2 feet) i*estiiig unevenly upon 



Fine chalky gravel, with some large subangular flints and 



pebbles of quartzite, sandstone, limestone, schist, &c. ...9 feet. 



Large bones are said to have been found in this gravel by 

 the workmen. 



Below Known's Folly the modern little stream deserts the 

 course of the more ancient channel, and has excavated for 

 itself a shallow valley in which it runs north-westward towards 

 Foulmire, while the older gravels are continued along a more 

 easterly line, outliers of them being found on the slope of the 

 hills by North Hall, Sharpens, Heydon Grange and onwards to 

 Whittlesford. 



About North Hall some thickness of chalky gravel and sand 

 is found, the stones being mostl}^ pebbles of chalk and flint, but 

 there are many boulders of quartzite, grit and basalt. Near 

 the farm called Sharpens a small pit exposes 10 feet of very 

 chalky gravel, evidently occupying the old channel in the 

 chalk, but now forming a ridge into which the beds dip on 

 each side ; sandy and loamy layers are interbedded with the 

 gravel, and the proportion of chalk stones is in places more 

 than 50 per cent.^ North-eastward by Heydon Grange the 



1 Details regarding this disturbance and depression are given in the Geo- 

 logical Survey Memoir, on sheet 47, now in the press. 



2 For the notes on these and other Gravel pits I am indebted to Mr W. H. 

 Penning, of H. M. Geological Survey, and I have since had the advantage of 

 visiting some of them uucler his guidance. 



