Dr. FiTTON on the Strata below the Chalk. 255 



ward, to their final disappearance near Pyt-house. The remoter portions of this formation, on the 

 north-west, form some of the highest ground within the surrounding ranges of green-sand, — 

 as at Higher Lawn, Newtown, Pythouse, Linley, and Summerleaze ; rising at the first two of 

 these places, nearly as high as the summit of Stop-Beacon, and out-topping the chalk immediately 

 on the north of the valley. The hill at Newtown is higher than the top of Castleditches. 



The disposition of the beds on both sides of the Nadder westward, accords with that in the eastern 

 portion of the valley ; the dip at Chicksgrove Mill being about east 25° south ; and at an old quarry 

 near the syllable -ton in the word Hazelton of the Ordnance Map, south about 40° east. On the 

 south of the road from Newtown, immediately below the letters ho in the word Pylhouse, the dip 

 is likewise nearly south, at an angle of about 22°, but this rapid inclination may be, in part, the 

 result of subsidence. On the north of the anticlinal line the beds dip rapidly in an opposite 

 direction. Thus, at Linley on the west of Lower Lawn and Summerleaze, and on the north of 

 Ashley Wood east of the line of Ponds, where the Portland strata come very near to the ridge of 

 Upper green-sand, the dip is almost directly north. In a quarry west of the road from Tisbury 

 to Fonthill, it is north 30° east, at an angle of about 20°, and the beds are much shattered by 

 fissures. 



Excellent sections of the upper Portland beds are displayed in the quarries on the ravine 

 between the village of Chilmark and Penthurst Bridge (See PL X. a., No. 13, line A B.) ; where 

 the strata are inclined to the east 10° south, between 3° and 4°. Among the loose matter at the 

 top of these quarries is botryoidal carbonate of lime, passing into compact freshwater limestone, 

 — like the "Cap" of Portland, and the stone called "malm", at Garsington in Oxfordshire. 

 The uppermost Portland beds here afford beautiful specimens of a fine-grained oolite like that 

 of the " roche " in Portland : but the stone in some places alternates with sand, and has, in 

 general, a very sandy character. 



The principal quarries of the Vale of Wardour are in the vicinity of Tisbury ; and some of the 

 best, when I was in the country, were near the road from that village to Fonthill GifFord, The 

 stone is more like that of this formation in the Isle of Purbeck, than in Portland itself, and 

 of a darker hue. A continuous bed of flint, about 2 inches thick, in one of these quarries 

 (Bevis's) had supplied, I was informed, the beautiful specimens of corals in chalcedony, which 

 are found in collections from this part of England. Among the fossils I obtained at Tisbury are 

 Astarte cuneata, Ammonites biplex in chalcedonic flint ; Ammonites giganteus of great size, Nerita 

 sinuosa, Terehra Portlandica, Turritella excavata (Cerithium ? excavatum). A full enumeration of 

 the species found here, and generally of the fossils of the Vale of Wardour, was drawn up by 

 Miss Benett for Sir R. ColtHoare's History of Wiltshire; separate copies of which, illustrated by 

 plates of some of the new species, have been presented by that lady to her friends *. 



The continuity of the strata hereabouts is frequently interrupted by chasms, locally called "lets ", 

 like those of Portland {supra, p. 218.) and of Oxfordshire; in which the beds are abruptly 

 broken off, and the intervals filled with rubble and looser materials, to a perfectly level surface, 

 covered with a uniform coat of vegetable soil. 



Portland Sand. — I saw no place in the Vale of Wardour in which the beds immediately beneath 

 the Portland stone were exposed ; but I believe that the Portland sand occupies a great part of 

 the descent from Pythouse to the plain on the west of it ; and in crossing from Newtown to Ha- 

 zelton this group seems to be disclosed immediately below the latter village, springs breaking out 

 along the line of contact. If this be correct, the bluish gray strata, occasionally visible in the 



* " A Catalogue of the Organic Remains of the County of Wilts," 4to, Warminster, 1831. 

 VOL. IV. SECOND SERIES. 2 L 



