1823.] Mr. Farey on the Pontefract Sandstone Rock. 275 



surrounded by dots for colouring on the map of my friend. In 

 the next place, a hummock of the Pontefract rock has been 

 omitted on the north-west side of Bardsea village (Derb. Rep. 

 ii. 410, note). Another is omitted under East Keswick village; 

 and a point of the same rock, north of the Wharfe River, extend- 

 ing from near Wood Hall, under Carlston Hill House, where 

 there are gritstone quarries in it. 



In addition to which, my friend has omitted to show a remark- 

 able denudation, through which the Wharfe River passes in 

 Collingham parish ; wherein for 14- mile in a north-west and 

 south-east direction, and a mile in some places, transversely 

 measured, the second coal shale is laid bare of its unconforma- 

 ble coverings. Also the southernmost of two singular hum- 

 mocks of the limestone on the neck of the Pontefract rock sepa- 

 rating this denudated tract from the coal-field, is omitted. 



I must now return to the border of Derbyshire, and speak of 

 the rock which Mr. Smith marks (n), and denominates " flag- 

 stone : "* it is my fourth grit rock (Derb. Rep. i. 164, 423, and 

 427, &c), and my third coal shale lies under and west of it, pro- 

 ducing, as Mr. S. truly states, " ganister stone," to which I will 

 add, excellent fire clay, which are its chief characteristics. 

 From near Sheffield, past Penistone, Huddersfield, and Halifax, 

 and so on north-westward to near Swill Hill, the range of this 

 fourth rock is shown with sufficient accuracy, except as to the 

 double commencement and western of the two courses coloured 

 for this rock, from Whirlow to Stock Bridge ; but the remainder 

 of its course on the map I consider to be completely erroneous. 



Near to Swill Hill, this fourth rock has arrived at its most 

 western extension in the bottom of the general trough in the 

 I 'orkshire coalfield, which trough-line ranges from somewhere near 

 South- Elmsal, already hinted at in p. 273, as a place south-east of 

 Wakefield, at the edge of the Pontefract rock, and probably 

 passes Wakefield, Wood church, Birstal, and High Farnley, on 

 the north-east in each instance, and thence near Swill Hill, and 

 so on, passing south of Pendle Hill, into the Burnley and Black- 

 burn coal-field, in Lancashire. 



From the bottom line of this important trough, near to Swill 

 Hill, the basset edge of this celebrated fourth rock, has a general 

 course of about east-north-east, passing, I believe, along the 

 northern verge of Bradford Dale to the town of Bradford ; from 

 whence I have ascertained its course to be along, or not far from, 

 the Toll Road towards Leeds, until within half a mile of Kirk- 

 stal Bridge, when this rock descends obliquely under Armley 

 Hall, and crosses the Air River about a mile below the Bridge ; 

 from whence its course is for the next mile about north-north- 

 west, between Kirkstal and Burley. From hence an east-north- 



* Which is an ill-chosen name ; because half a dozen of the lower coal-measure 

 rocks, produce, in particular quarries, excellent flagstones, difficultly distinguishable 

 from those of the fourth rock. 



t2 



