Dr. FiTTON on the Strata below the Chalk. 291 



Church Farm on the \vest of Wing, — and again at North Tinkershole south of Stewkley, on the 

 north of Dunton, and west of Hogstone, — it would seem that the upper part of most of the flat- 

 topped heights tliereabouts may have once been occupied by this formation*. 



The Portland strata also occur at Weedon on the south of Whitchurch, about midway to 

 Bierton, the western part of which village stands upon them. But I was assured that no stone had 

 been obtained, though often sought for, at Cublington, Aston Abbots, and Wingrove ; the two 

 places last mentioned affording only sand and gravel f. 



The Portland sand is little disclosed near Aylesbury ; though it comes to the surface around 

 the town beneath a thin capping of Portland stone. The road from Tring to Aylesbury, a little 

 west of the 37th milestone, is crossed by sand, which includes green particles and worn fragments 

 of black flint ; and the subjacent clay makes its appearance close to Aylesbury on the north. One 

 of the most distinct sections of the sand was visible at the entrance of Whitchurch, where the 

 road to Aston Abbots strikes off from the main. A good section also was obtained from com- 

 bining that of one of the pits at the Warren near Tinkershole on the south of Stewkley, with 

 another north of Dunton. 



Whitchurch, at the cross-road to Aston Abbots. 

 \_Lorver green-sand 'i 2 



1. Yellowish sandy soil. 



2. Greenish and reddish sandy clay. 



[Porlland Sand.^ Ft. In. 



3. Concretional soft stone, in irregular lumps, full of green particles ; with numerous shells; 1 . 



Venericardia, Pernte. Compare with that of the Section near Thame; 2, p. 282. . . J 



4. Harder stone, in irregular concretions, abounding in green particles, and containing worn 



fragments of blackish flint or chert. Very large specimens of Amrtionites biplex, as on 

 the shore near La Creche, Boulonnois ; Pecten concentricus ; large Venericardia 



\_Kimmeridge Clay.^ 



5. Dark bluish clay, continuous with that of the descent towards Hardwick, and thence to 



Aylesbury ; here dug to the depth of about 20 feet, and used for making tiles. It 

 contains Septaria, and nodular masses of phosphate of lime, — ^which, when acted upon 

 by marine acid, afford the peculiar smell of Coprolite, though they have not its form. 

 Among the fossils here are channelled Belemnites. 



Pit at The Warren, south of Stejtkley. 



Soil and whitish rubble about 2 



\_Purbeck.2 



1. a. Light yellowish grey clay, passing into stone 1 0"1^ 



b. Rubbly limestone 9 j 



{^Portland Stone.l 



2. Soft, uniform, marly limestone, abounding in fossils ; — Ostrea expansa ; Pecten lamello- "i 



5MS, Buccinuni naticdide, PI. XXIII. fig. 4, Perna quadrata, Pleurotomaria, Trigoniae, >6 

 Venericardia, and large Ammonites = 4 ft. to J 



* Moor Hill, a height about a mile and a half north-west of tlie village of Quainton, has a 

 nearly horizontal top ; and, not improbably, is capped with Portland stone or sand. 



t Smith's map of Buckinghamshire represents the Gault as extending to the north-west from 

 between Hulcot and Wing, as far as Cublington and thence to Cottesloe. If this be correct, the 

 Portland beds may exist within that space, at a depth below the surface at least equal to the 

 thickness of the Lower green-sand in this part of the country : but the map near Aylesbury re- 

 quires much correction. 



