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



only refer to their account of them*, and to our own detailed section of Black 

 Nore on the west cliff of the Isle of Portlandf. We have little to add to what 

 these authors have published, except the occurrence of bones of Saurians 

 which we discovered in the cliff of Black Nore, imbedded in compact Port- 

 land stone. 



We have stated in our introduction that this district contains two distinct 

 ranges of Portland stone ; one constituting the table-land of the Isle of 

 Portland, dipping southwards beneath the sea, and rising with an elevated 

 escarpment northwards towards the bay and valley of Weymouth ; the other 

 constituting a long and narrow line of elevated hills, parallel, and immediately 

 subjacent, to the chalk escarpment of the Ridgeway, and presenting a con- 

 tinuous and lofty escarpment towards the south. In fact, these hills occupy 

 the position which in districts that have been less disturbed is usually held by 

 the sub-escarpments of the greensand formation, where it emerges regularly 

 from beneath the chalk : such are the escarpments of greensand which in 

 Kent and Sussex extend from Folkstone, by Coxheath, Nutfield, and Leith 

 Hill, to Godalming. A glance at our map will show that along the northern 

 frontier of the Vale of Weymouth this ridge of Portland stone forms a con- 

 tinuous band from the east extremity of our district near White Nore to 

 Portisham, where it suddenly terminates in the great fault, and is found no- 

 where further west in England. Along nearly the whole of this tract it attains 

 a high elevation, rising near the central part at least 500 feet into the lofty 

 eminences of Preston Hill, Charlbury, and Bincombe Hill : at these three 

 places its elevation is little less than that of the chalk itself. On the west of 

 Upway it forms a narrow ridge or hog's back from Upway to Portisham, 

 known by the name of Gorton Hill and Waddon, dipping at an angle of 

 about 45° to the north. Although these Portland beds dip thus rapidly to 

 the north, through great part of the range now under consideration, yet 

 such is the dislocation and elevation they have suffered along the line of the 

 great fault, that their northern margin is seldom brought into contact with 

 any other strata than the chalk. On the west of Upway this line of contact 

 is marked by a longitudinal valley, flanked on its north side by the chalk 

 escarpment, and on its south side by the upper Portland strata of Gorton 

 Hill;}: : thus, the Portland beds dipping to the north in Gorton Hill, and south 

 along the fault, form a trough in which reposes a long and narrow strip of 

 Purbeck strata, extending more than a mile both on the east and west of 

 Upway, and dipping conformably to the double dip of the subjacent Portland 



* Geological Transactions, Second Series, vol. ii. p. 37, &c. Outlines of the Geology of En- 

 gland and Wales, p. 172. f Plate III. fig. 3. J See Map, Plate I. 



