THE CORALLTAN ROCKS OF ENGLAND. 311 



as to what these beds represent ; but at least we learn that the Rag 

 of Headington is lost ere this. 



If we go to the east we see it disappear also ; but its place is 

 taken by the false-bedded limestones that were seen overlying it at 

 Shotover ; for it is beds of this series that we think are to be seen 

 in the great quarries at Wheatley. The amount of stone that is 

 or has been excavated here is something extraordinary, but scarcely 

 less so than the rarity of recognizable fossils ; just as in the stone at 

 Shotover, they are all ground down and obliterated. Nevertheless 

 Ammonites plicatilu, Belemnites abbreviatus, Exogyra nana and 

 Cidaris florigemma have here been noted, and reptile bones have 

 been known to occur. These beds, measured perpendicularly to their 

 apparent dip, have a thickness of 70 feet in one quarry alone ; and 

 as the dip, wherever observed, is easterly, or partially so, we should 

 have to allow some considerable additional amount if measured in 

 this way. The exceedingly local nature, however, of this vast 

 accumulation leads us to the conclusion that we are here viewing 

 false dip, such as may be seen in the corresponding beds at Head- 

 ington. We are here, then, presented with the deposits which were 

 formed on the extreme edge, not only of the coral reef, whose 

 thickness would not account for so much false dip (which amounts 

 in the most easterly quarry to 12°, and is even marked at 18° at 

 another spot on the map), but probably of the Lower Calcareous 

 Grit sandbank also — a conclusion which is supported by the fact of 

 its apparent sudden termination eastwards, and the immediate 

 succession of Kimmeridge (?) Clay. Nevertheless, considering it 

 coeval with the Shotover limestones, it is of supracoralline age. 

 The character of the stone here is variable ; but it contains good 

 facing- stones. There are blue-hearted limestones, grey oolites, 

 loose oolitic grit, and rubbly oolite, with clay partings towards 

 the base. 



These Wheatley quarries are a kind of expiring effort on the part 

 of the Corallian formation ; for, magnificent as they are, all signs of 

 them, or of any other part of the formation, suddenly disappear on 

 the north-east of a line between Stanton St. John and Holton. Pro- 

 fessor Phillips has noticed, in his ' Geology of Oxford,' that the 

 Lower Calcareous Grit forms what we may call an isolated sandbank 

 at Studley, whence he has named some fossils ; but of the vast 

 spread of this rock, marked in the Surve} 1, map between Holton and 

 Brill, not a trace can be seen. No sand-pits or quarries are to be 

 heard of; and the whole soil indicates a stiff clay beneath. Indeed 

 the Corallian formation has died out, not gradually, but suddenly, 

 and the normal pelolithic formation reigns supreme. 



In this range from Westbury to Wheatley the most remarkable 

 feature is the variety exhibited by this essentially variable set of beds, 

 a good idea of which can scarcely be obtained by the aid of words, 

 even though more details should be given. We therefore present 

 a generalized section (fig. 8) along a line following the range, with 

 beds at a moderate distance on either side projected on it ; so that it 

 must be considered diagrammatic, and the thickness only approximate, 



