10 Prof. BucKLAND and Mr. De la Beche on the 



runs along this escarpment brings up into absolute contact with the chalk. 

 At these two places^ however^ its thickness is so great as to leave little doubt 

 that it continues in its proper place beneath the chalky to the west extremity 

 of the fault near Abbotsbury, where it is again exposed^ and forms a con- 

 siderable feature in the escarpment of White Hill, overhanging the village 

 of Abbotsbury, and projecting thence nearly two miles westward into the 

 summit of the long and elevated ridge of Abbotsbury Castle. From Abbots- 

 bury Castle it turns northward, still forming the sub-escarpment of the 

 chalk, along the entire east and north frontier of the Vale of Bredy. It ap- 

 pears also on the summit of Swyre Knoll, Hammerdon Hill, and Shipton 

 Beacon, which form three remarkable outlying hills on the flanks of the Vale 

 of Bredy, and in much greater force on the summits of the insulated hills of 

 Golden Cap, Hadden Hill, Stonebarrow Hill, Coneygore, and Conig Castle 

 near Charmouth ; and further north, on the lofty tops of Lewsdon Hill, 

 Pillesdon Hill, and Black Down near Broadwindsor*. In the escarpment on 

 the north of Abbotsbury we have a distinct section, displaying ledges of hard 

 coarse limestone, loaded with grains of quartz and silicate of iron, and alter- 

 nating with thick strata of chert ; a little further west, at Abbotsbury Castle, 

 the calcareous matter ceases, and is replaced by strata of chert. These cal- 

 careous and cherty strata of the greensand at Abbotsbury, afford an interest- 

 ing object of comparison with those in the neighbourhood of Lyme Regis, 

 described by Mr. De la Beche f, as well as with those at White Nore. The 

 occasional presence of so much calcareous matter in the greensand, seems 

 to justify the appellation of craie chloritee, given by the French to the upper- 

 most strata of the greensand formation. 



The greensand in our Weymouth district is found to overlie and repose 

 successively on formations of different ages ; thus, in the valley of Upton on 

 the east of Osmington it rests on the Purbeck beds| ; in the south escarpment 

 of Upton Hill towards Ringstead Bay, on Portland stone§ ; on the west 

 of Osmington Mill, on Kimmeridge clay||; at Abbotsbury Common, on a 

 clay which is probably the Oxford clayH; at Golden Cap Hill, on inferior 

 oolite**; near Lyme Regis, upon liasff ; and at Axmouth and Beer, upon 

 red marl];;};. The same overlapping disposition of the greensand has been ob- 



* See Map, Plate I. t Geological Transactions, Second Series, vol. ii. pp. 109, &c. 



+ See Plate II. fig. 2 & 3. § See Plate II. fig. 2. 



II See Plate II. fig. 9. % See Plate II. fig. 6 & 7. 



** Geological Transactions, Second Series, vol. i. Part I. Plate VIII. and Plate XIV. No. 1. In 

 these sections the inferior oolite was omitted by mistake, but is inserted in a section of the same 

 coast, in PI. III. of Mr. De la Beche's Sections and Views Illustrative of Geological Phaenomena. 



tt Ibid. Plate VIII. ++ Ibid. Plate XIV. No. 2. 



