TKUNKS IN QCATERXART SANDS AT READING. 



297 



unworn and have sharp 

 edges ; they must have been 

 transported by floating ice- 

 blocks and so have escaped 

 rolling. Plint casts of A^i- 

 anchytes and Galerites are 

 tolerably common ; and one 

 good example of a Yentri- 

 culite was found. Of the 

 more perishable constituents 

 of the Chalk, a few rounded 

 nodules of hard chalk and 

 a worn fragment of Ino- 

 ceramus-sh.e\l were found. 



(/3) Tertiaries. There is 

 a considerable proportion of 

 rounded flints derived from 

 the destruction of these 

 beds. A fair specimen of 

 Ostrea hellovacina from the 

 same source was also found, 

 (y) High-level gravels. 

 There occurs, thinly scat- 

 tered through all parts of 

 the gravel, a small propor- 

 tion of rounded quartzite 

 masses derived from the 

 waste of the high-level gra- 

 vels that once formed an 

 uninterrupted layer across 

 the then un excavated valley. 

 (3) Occasional elements 

 transported from a distance. 

 Worn fragments of Ostrea 

 (chiefly 0. dilaiata) occur ; 

 and one worn Nerincea was 

 found from the Oolites near 

 Oxford. A small piece of 

 blue, flssile limestone, when 

 broken, showed the charac- 

 teristic structure of Forest Marble. This must have been carried 

 41 miles if derived from the nearest source, Islip on the river 

 Ray, and if it followed the general direction of the river-valley 

 without taking the sinuous curves of a river. 



This description holds good for all the gravels of the four faces of 

 the pit. The west and north are still well seen ; the east and south 

 are now entirely covered up. 



B. The reconstructed beds, about 9 feet thick. These consist of Tertiary 

 elements (Woolwich and Beading beds, and to some extent the basement 

 Q.J.G.S. No. 142. X 



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