Dr. C. Callaway — Glacial Clay on Cotteswold Plateau, 217 



The brown clay, treated in the same way, presents very marked 

 -differences. More than one-half of it is a quartzose sand of angular 

 -and subangular grains stained with a reddish-brown colour, the 

 remainder being a pale-red clay with a small proportion of minute 

 •clear minerals. 



The Erratics. — These are of all sizes up to 3 inch diameter. The 

 'following are the chief varieties : — 



(1) Quartz, very much rolled. 



(2) Quartzite, (a) white and (6) grey, well rolled. 



(3) Cliert, (a) white, (6) grey, with impressions of small encrinite 



stems, and (c) banded black and white ; not so well rolled 

 as the quartz and quartzite ; some specimens subangular. 



(4) Coarse quartzose grits, grey and reddish (? Millstone-grit) ; 



well rounded. ' 



(5) Flints, (a) brown with white crust, (6) white (? weathered) ; 



rounded and subangular ; 1 to 2 inches diameter. 



(6) Brown ironstone (? Lias Marlstone), small, subangular. 



(7) Grey oolite, subangular fragments and numerous spherical 



grains. 



(8) Eeddish-brown iron-shot oolite : locality not identified, though 



a specimen was submitted to several experts. 



Derivation of the Materials. — The origin of the clays is not 

 •determined with certainty. The blue variety suggests the Lower 

 .Lias, while the red sandy clay may have been derived from Keuper 

 Marls and Sandstone. 



The pebbles of quartz and quartzite have almost certainly come 

 from Triassic conglomerates north of the Cotteswold area. The 

 cherts and grits are presumably Carboniferous, and may have 

 travelled from Derbyshire. For the flints a north-easterly origin is 

 probable. The ironstone and oolites, with perhaps the blue clay, are 

 •the only materials that appear to be of local derivation. 



Some light is thrown upon the derivation of the erratics by 

 ■a study of the deposits which occupy the Evenlode valley and the 

 northerly extension of its axis along the valley of the Stour, which 

 drains into the system of the Warwickshire Avon. Commencing at 

 -the southern point, we obsei've exposures of sand and clay at Milton- 

 nnder-Wj'chwood, a mile and a half east of our Tangley section, 

 about 250 feet lower than the section, 100 feet above the Evenlode at 

 Shipton, and 400 feet above O.D. The highest deposit is near the 

 -road at Upper Milton. It consists of sands, brown and grey inter- 

 bedded, excavated to a depth of 10 feet, and overlain by from 1 to 

 3 feet of brown clay containing quartz pebbles and small angular 

 flints. There is a similar clay in a field to the east at a little lower 

 level. It is 3 to 4 feet thick, and is traversed by a rough vertical 

 jointing. Shaken up in water, it is seen to resemble the brown clay 

 of the Tangley section. About 100 yards distant is a section of 

 clay, with quartzite pebbles, overlying a gravel of small angular 

 ^pieces of oolite, underlain by red sand. It will be noticed that the 

 uppermost layer in these three sections is a brown sandy clay, not 

 dissimilar to the brown clay of the ridge above. 



