Dr. FiTTON on the Strata below the Chalk. 247 



that which immediately succeeds the chalk, the equivalent of the fire-stone of Surrey, and the 

 Malm-rock of Western Sussex, abounding in chert. To the lower portion the term Green-sand 

 is strictly applicable, as it is composed of sand, and abounds in green particles. 



About two miles west of Ridge the sands suddenly expand and occupy a large space from the 

 north of Fonthill Abbey to Stop Beacon, where the surface is strewed with fragments of chert, 

 the remains, probably, of the higher beds which have disappeared. But further west, between 

 the Abbey and East Knoyle through Middlemore, the ridge again is narrow and highly inclined ; 

 but so much reduced in height, that the chalk of Hindon can be seen over it from the flat country 

 at the mouth of the vale. The sands again expand a little on the west of East Knoyle ; but at 

 Upton their dip is not much less than 40°; so that the horizontal section occupies but a few paces, 

 and on the north the chalk is seen at a lower level, connected by insensible gradation with the 

 sands. 



(129.) Gault. — The clay beneath the Upper green-sand seems to be co- 

 extensive with that formation. It forms on the south of the Vale of War- 

 dour a rapid slope; on the north, a depression,, immediately below the 

 sand ; and is identified in several places with the gault of the eastern coun- 

 ties by the characteristic fossils. At Lower Donhead, under Lidhurst, it 

 contains Ammonites with coproid masses of phosphate of lime ; and at 

 Ridge, where one of the most distinct sections is exposed, many other fossils 

 have been found, the clay having been long used for tile-making. The beds 

 all dip to the north, between 6° and 7° ; and a well has been sunk through 

 the clay, and a thin bed of sand beneath it, down to the Purbeck strata ; 

 the order being thus : — 



Section at the Tile-pits, Ridge. 



South. Purbeck Upper Green-sand. North. 



Sione-pit. Sand- Gault. Tile-pits. Well. a<3^5. 



75 

 IS 



Ft. In. 



1 . Upper Green-sand, at the upper part of the hill, consisting of — 



a. Green-sand. 



b. Green sand-stone, full of Gryphcea vesiculosa at the upper part 8 to 10 ft. 



c. Greenish sand more than 30 



d. A bed called by the workmen " malm-rock"; sand with stems of Siphonial ^^ 



and impressions of Ammonites about/ ■. qq ,. 



2. Gault, including near the top a bed of pyrites, shot through with veins of calcareous ^ 



spar, of which some large crystals are found here. The rest is clay* containing I _^ 

 Ammonites, and other characteristic fossils, with Septaria and ovoid concretional | 

 masses of phosphate of lime J 



* About 3 feet of clay, which occurs on the north-west of Ladydown, may belong either to 

 this stratum, or to one of the beds subordinate to the Purbeck formation. 



VOL. IV. SECOND SERIES. 2 R 



