156 



T. E. LONES — GRAVELS, SANDS, CLAYS, 



Clay-with-Flints. 



In the year 1861 Mr. Whitaker, a past President of this Society, 

 applied the term " clay-with-flints " to a deposit of stiff brown 

 or reddish clay containing large unworn flints, and occurring very 

 irregularly upon the Upper Chalk. This clay-with-flints can be 

 seen at many places on the higher parts of the undulating country 

 before referred to, and especially during an ascent from one of 

 the river-valleys towards the summit of the neighbouring Chalk 

 hills. The clay does not, in general, occur in the lower parts 

 of the valleys, but may be seen over a strip of country of variable 

 width as soon as a certain height has been reached. Thus, anyone 

 ascending the eastern side of the picturesque hill on which 

 Wigginton stands, may see the clay-with-flints as soon as a height 

 of about fifty feet above the Tring road has been attained. Sections 

 3, 4, and 5 represent beds exposed near Wigginton, at different 

 heights. The clay-with-flints is shown in the portion marked 

 B on Section 5. There is a marked relationship between the 

 contours of the country and the distribution of the clay-with-flints, 

 and this fact has been utilized in drawing some of the boundaries 

 of the deposit on the map. 



Sections 3, 4, & 5. — Near "Wigginton. 



3 -?-^S= 



A 

 B 



B 



Soil. 



A. Brown clayey gravel. 



B. Redbrick-earth. 



C. Brown clayey gravel. 



A. 

 B. 



Soil. 



Coarse gravel, 

 or clayey. 



sandy 



A. Soil. 



B. (nav-with-flints. 



C. Chalk. 



The colour of the clay-with-flints is usually a deep reddish- 

 brown, passing near the junction with the Chalk into a darker 

 brown or a nearly black shade. This darkness of colour is mainly 

 due to the presence of oxide of manganese, as a simple chemical 

 analysis will show. The clay contains unworn flints, which appear 

 as if they had been directly derived from the Chalk, and it is 

 often mixed with loam and flint- pebbles probably derived from 

 overlying beds which have been denuded away. In many places 



