48 Rev. A. Sedgwick on the Geological Relations and 



From these quarries the limestone rises into ridges of considerable elevation ; but they are so 

 much rounded oft' by denudation, and so nearly bordering on other hills to the north-west, that 

 the demarcation is not easily traced. The line passes round the ridge of Iloughton.le-Sidc, in a 

 direction about north by west, crosses the turnpike road, and ranges on a plateau to a point about 

 three hundred feet west of Wiiite House, from which point it returns and passes on the north side 

 of Shackerton Hill. Under this hill there is a deep denudation, which has probably removed all 

 the magnesian limestone. The demarcation appears to range in an undulating line bearing to the 

 north-east, encloses Tod Fall, and crosses a rivulet a few hundred yards above Red House. On 

 tlie other side of the rivulet the line ascends nearly due west, and encloses Newbiggen ; beyond 

 which place it is again deeply indented to the east by another valley of denudation, and then 

 ascends to a point on the top of the next ridge about half a mile south of the Engine House. From 

 thence it returns (enclosing the lime quarries of West Thickley) in a direction nearly due east, 

 skirting for about two miles the south side of a remarkable denudation, which affords a passage to 

 the great Stockton rail road. In this course it passes on the north side of Midderidge Grange, 

 and crosses the rail road at Midderidge quarry. 



Commencing at the last-mentioned quarry, the line passes under East Thickley, bearing nearly 

 due west ; afterwards sweeps round towards the north, forming all the higher part of the ridge 

 which extends from East Thickley towards Shildon, and continuing its range on the summit of 

 the high lands, passes immediately to the west of the old Shildon coal-pits and of the village of 

 Eldon. From Eldon it sweeps round the west side of the plantation, deflects to the north-east, 

 crosses a deep denudation where a considerable part of the escarpment has disappeared ; then 

 passes through a plantation south of Howlish Hall, and afterwards ranges considerably to the 

 west, forming the cap of Cowndon Grange Hill. The line again deflects to the east, and the 

 limestone forms the crown of the hills immediately west of Cowndon, and from thence ranges to 

 Westerton. I have been the more minute in these details, because this part of the western demar- 

 cation of the magnesian limestone is not easily ascertained, and is not correctly laid down in the 

 geological map of the county of Durham published in the year 1824. 



P'rom the neighbourhood of Westerton to Painshaw Hill near the south bank of the river Wear, 

 the line of demarcation is much more plainly indicated by the natural features of the country ; for 

 the limestone again forms the crown of a great irregular terrace, the lower part of which is com- 

 posed of beds subordinate to the Durham coal-field. To this arrangement there are, however, 

 the following exceptions: — 1. At Cowndon quarries, whicli are on the edge of the escarpment 

 about a mile south of Westerton, the limc-itone is thrown out of its position, and made to abut 

 against the sandstone. 2. At Westerton the escarpment is entirely composed of sandstone. The 

 yellow limestone ranges at the same level (probably in consequence of a fault) on the north-east 

 side of the village. 3. By a similar cause the inferior beds are brought to the top of the escarp, 

 ment at Newbottle, part of which place stands on sandstone. 4. To the east of Hetton-le- 

 Hole the limestone forms the whole escarpment ; and some inferior beds of the formation extend 

 from the base of the hills, which are in the general direction of the boundary to the western ex. 

 tremity of the village. With these exceptions, the magnesian terrace possesses the structure above 

 described, and its range is defined by the following places, which stand very near its edge, viz. 

 Merrington, Ferry Hill, Thrislington, Cornforth, Coxhoe Hall, Quarrington Hill, Cassop, 

 Running Waters, Moorsley, Great Eppleton, High Downs, Newbottle, West Herrington, and 

 Painshaw Hill. Black Gate, Quarrington, Sherburn, North Pittington, West Herrington, and 

 Houghton.le. Spring, are immediately on the west side of the line of demarcation. 



This part of the range is, on the whole, well represented by Smith, with the exception of a long 



