A HISTORY OF BERKSHIRE 



during the continental period, for no remains have been found prob- 

 ably any that existed were washed away when depression again set in 

 and the sea waves advanced over Berkshire. In any case our next 

 deposit, the Lower Greensand, is, in so far as this county is concerned, 

 of marine origin, and owing to the earth movements which had taken 

 place since the deposit of the underlying strata it rests upon them in an 

 unconformable manner. The effect of this unconformity is an overlap 

 which is very clearly indicated on the geological map, for it will be 

 observed that the Lower Greensand does not cross the county in a band 

 parallel to the older series but occurs in an irregular and patchy way. 



The largest patch extends from Uffington almost to Faringdon, and 

 near that place are two small outliers. There is a narrow line between 

 Bourton and Compton Beauchamp, a patch near Drayton, and three 

 outliers near Wootton and Cumnor. 



The Lower Greensand of Faringdon is of great interest, indeed the 

 sponge gravel found there is probably the most interesting geological 

 deposit in Berkshire. 



In 1850 a party of geologists, Professor Edward Forbes, Mr. Sharpe, 

 Mr. (afterwards Sir Joseph) Prestwich, Mr. Tylor, Mr. Cunnington, 

 and Mr. R. A. C. Austen visited Faringdon, and the results of their 

 investigation are given in a paper by the last named published by the 

 Geological Society. 1 



He remarks : ' What seemed to render this district more peculiarly 

 interesting was the circumstance that it included the beds at Faringdon, 

 so well known from their fossils, as far back as the catalogue of Llwyd, 

 1759, described by Dr. Fitton 2 as outlying masses of lower greensand, 

 and considered by him to be especially deserving of notice ; also that 

 published lists afforded indications of fossil forms peculiar to this portion 

 of the Cretaceous series and limited to a few localities, and which seemed 

 to present a wide departure from the ordinary conditions which influenced 

 the Lower Cretaceous deposits, such as the numerous and perfect Amor- 

 phozoa at Faringdon.' The late Mr. C. J. A. Meyer made a careful 

 study of these beds and divided them into three divisions : 



1. The lowest the calcareous sponge gravel. 



2. Above it the red gravel. 



3. At the top ferruginous sands with ironstone. 



The sponge gravel is seen in the pit known as the Windmill pit 

 or Ballard's pit north of the village of Little Coxwell ; it is about 30 feet 

 thick, is fairly well and evenly stratified, and is crowded with fossil sponges 

 and shells. Portions of the beds are here and there consolidated into 

 calcareous masses. The shells are mostly brachiopoda, both Rhynchonella 

 and Terebratula are abundant and belong to several species. The valves 

 are often united, but single valves are quite common, they have not 

 however been at all rolled or waterworn. Many bryozoa are to be 

 found and are in beautiful preservation, but it is the sponges which 

 have made Faringdon celebrated, and they occur in vast abundance. 



1 Q uart - 7un>- Geol. Sx. (1850), vi. 454. Geol. Tram. iv. part ii. ser. 2,271. 



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