182 MESSRS. KIRKBY AND DUFF ON THE 



annelid, Microconchus carbonarius, constitute about all the spe- 

 cies of animal life that have come under our notice. 



BOUNDARY OF THE COAL-FIELD TO THE SOUTH. 



It is an unsettled point with mining men whether in Durham 

 workable coal is to be found in the region lying to the south of 

 the existing collieries. It is thought by some that good coal 

 exists considerably to the south of the district under notice — 

 where to our eyes there is nothing but unprofitable Millstone 

 Grit. And in the east of the county there are those who hold 

 that the Coal Measures are continued southward beneath the 

 Permian and Triassic rocks, as in some other parts of England. 

 The following remarks bear on the question chiefly as it relates 

 to the former district, where the range and disposition of the 

 Coal Measures are not masked by overlying rocks. 



The most southerly colliery now going in Durham is that of 

 New Copley, on Cockfield Fell, where the Brockwell, Five Quar- 

 ter, Harvey, and another seam have been proved on the south 

 side of a great fault with a downthrow south. In former years 

 the Brockwell seam was wrought in the Three Sisters Pit, a little 

 more to the east. There are also abandoned pits a mile or two 

 further to the east at Paddock Mires, and near the Sun Inn, 

 which are still further to the south, where the Brockwell was 

 worked many years ago. Beyond these points we know of no 

 place where any seam of the Coal Measures has been worked. 



At the New Copley Colliery the Measures on the south of the 

 fault rise very rapidly, and soon crop out as shown in figure 15. 



At the old pit, near the Sun Inn, where the Brockwell was 

 got at a depth of twelve fathoms, the Measures also rise very 

 sharply to the south, in which direction the workings are said 

 to have ended against a fault with a downthrow south. 



About three miles west of Cockfield an outcrop of the Brock- 

 well seam is exposed in Arngill, the coal being over six feet 

 thick, and dipping to the north fully one in two. It is probable 

 that this is a piece of Coal Measures let in by the fault seen at 

 New Copley Colliery. 



