GEOLOGY 



place they form a band on the south of the Kennet past Inkpen and 

 extending almost to the county boundary. 



There are a number of outlying patches of Reading Beds, some 

 with cappings of London Clay. They mostly lie on rather high ground. 

 Then there are some small patches near Cookham and a large one near 

 Wargrave. Yattendon stands on one, and there is another near Fril- 

 sham. There are several north of Newbury, one of which runs out 

 from Newbury to Wickham. 



There are also a number of small outliers dotted about on the Chalk 

 near Basildon, Aldworth, Great Fawley, etc. 



The Reading Beds are a great deal hidden by alluvium and gravel. 

 They consist in the main of clay though important beds of sand occur. 

 The clay is often mottled, red, blue, orange, etc. Beds of pebbles occur 

 in places. The thickness, according to Mr. Blake, varies from about 

 70 to 90 feet, but it is a little less in places. Good supplies of water 

 are to be obtained from the sands and it is often soft in character. 



The Reading Beds, as has been said, rest upon a greatly eroded 

 surface of Chalk, but it is a fairly even surface and is usually covered 

 by holes or perforations filled with sand. These perforations are prob- 

 ably often the work of boring shell fish, or, as Mr. W. H. Hudleston 

 has suggested, they may in some cases be due to the roots of seaweed. 



Upon this Chalk floor lies the bottom bed of the Reading series 

 consisting of green loamy sand with pebbles of flint. These pebbles 

 are derived from the Chalk and show to what a large extent the Chalk 

 had been eroded before the deposition of the Reading Beds. 



The bottom bed also contains flints which are of irregular shapes 

 and have not been at all waterworn or rolled. They have become 

 externally green and are usually spoken of as ' green-coated flints.' 



At Reading, Newbury, Kintbury and other places this bottom bed 

 contains great numbers of oyster shells, usually Ostrea bellovacina, but at 

 least one other species occurs. The two valves of the oysters are fre- 

 quently united and they are not rolled or waterworn, showing that they 

 lived where we find them. 



In some places at Reading there are two distinct oyster beds a foot 

 or so apart. A few marine shells and many sharks' teeth occur in the 

 bed. 



This bed of oysters has long attracted attention. It is referred to 

 by Robert Plot in his Natural History of Oxfordshire (folio, Oxford, 1705), 

 p. 1 20. He remarks that ' at Cats Grove near Reading they met with 

 a bed of oyster shells both flat and gibbous about 12 or 14 foot under- 

 ground, not at all petrified, all of them opened except some very few 

 that I suppose have casually fallen together, which how they should 

 come there without a deluge seems a difficulty to most men not easily 

 avoided.' 



Dr. William Stukeley in Itinerarium Curiosum (folio, London, 1724), 

 p. 59, also refers to this locality. He says that 'near the trench the 

 Danes made between the river Kennet and the Thames is Catsgrove 



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