■1508 DR. A. M. DAVIES AND MR. J. PRINGLE ON [June I913, 



16. On Two Deep Borings at Calvert Station (North Bucking- 



' hamshire) and on the Paleozoic Floor north of the Thames. 



By Arthur Morley Davies, A.U.C.S., D.Sc, F.G.S., and 



John Pringle, of H.M. Geological Survey. (Read February 



5th, 1913.) 



[Plates XXXIII & XXXIV.] 



Contents. 



Page 



I. Introduction 398 



II. Description of the Borings 310 



(1) The Eastern Boring.— General Remarks 310 



(a) Jurassic Rocks 312 



(6) Palaeozoic Rocks 322 



(2) The Western Boring 326 



III. Palseontological Notes 329 



IV. The Bletchley Boring 332 



V. The Palaeozoic Floor north of the Thames 334 



VI. Summary 338 



I. Introduction. [A. M. D.] 

 'Calvert Station is situated on the main line of the Great Central 

 Railway, 49 miles by rail from London (Marylebone Station) by way 

 -of Aylesbury, and about 11 miles north-west of the latter town. 

 ' Calvert ' is not the name of any village or hamlet, but the station 

 was so named in memory of a former distinguished resident in the 

 neighbourhood, General Sir Harry Calvert. It will not be found, 

 therefore, on any map issued prior to the opening of the railway; 

 and, for the benefit of any observers who may seek to locate the 

 borings about to be described upon the only published geological 

 ■map of the district (the original 1-inch sheet, 45 S.E.), it may be 

 stated that the station lies in the south-eastern angle of the 

 T-shaped road-junction, about an eighth of an inch north of the 

 second ' n ' in ' Charndon Lodge.' The road — really a green lane — 

 which forms the stem of the T constitutes the boundary between 

 the parishes of Charndon on the west and Steeple Claydon on the 

 east. One of the borings is in the former parish, one in the latter. 

 Shortly after the opening of the railway in 1898, the late 

 Mr. Itter, of Peterborough, opened a branch of his brickworks 

 on the Charndon side of the green lane, and very extensive exca- 

 vations have been made in the shaly clays of the ornatum zone. 

 In 1905 a boring for water (hereinafter referred to as the Western 

 Boring) was made in the brickfield ; but only salt water was 

 obtained, and at a depth of 380 feet inflammable gas was met with 

 and has been coming off ever since. At 445 feet 8 inches the 

 boring was abandoned. No use was made of the gas, and six years 

 passed before its existence came to public knowledge, when, in 1911, 

 the Guildhall Syndicate was formed to make further investigations. 

 They set to work to clear out the Western Boring and carry it deeper 

 down, and at the same time started a new boring (which we call 



