320 Prof. Morris — Lead-mines of the North of England. 



ARGILLACEOUS AND ARENACEOUS. CALCAREOUS. 



FEET FEET 



Scar Limestone 30 



Hazle, Plate, and Coal 37 



Cockle-shell Limestone 2 



Hazle and Plate 102 



Tyne Bottom Limestone 24 



Whetstone Bed, etc 3 



Whin Sm. 



Turning now to tlie igneous rocks and commencing with the Whin 

 Sill, so called from its sometimes being apparently parallel to the 

 other strata, but really varying as much as 1000 feet when traced 

 over the whole area; it is from a few to 200 feet thick in Tees- 

 dale, giving a picturesque character to the scenery, and may be traced 

 through Northumberland, into Durham, Cumberland, and Yorkshire. 

 Its age is anterior to the fissures holding the lead, as they traverse it, 

 and also to the Penine fault, which may be contemporaneous with the 

 veins, the force producing the one causing the other. The whin is a 

 dolerite of augite and felspar, with titano-ferrite. Many dykes also 

 traverse this district. Two are comparatively well known — the Hett 

 dyke traverses the Mountain Limestone, Millstone Grit, and Coal- 

 measures, and the Cockfield dyke, about 70 miles in length, passing 

 through the Mountain Limestone, Millstone G-rit, and Coal-measures, 

 and New Eed Sandstone. This district is traversed by many Faults, 

 which have had a most imjDortant influence on the physical character 

 of the district, and to some extent upon the industrial resources. 

 The 90 fm. dyke (east and west), Tynedale fault, and Stublick dyke, 

 throw down the coal to the north and west — hence the Stublick, 

 Midgeholm, Conewood, and Hartley Burn coal-fields. The Penine 

 fault has a downthrow to the west of 3000 feet, which, with the 

 Craven fault, so materially influences the physical features of the dis- 

 trict traversed by them. The Burtreeford dyke is a north and south 

 fault, crossing the lead-mine district from the Yale of Tyne to the 

 Tees, afiecting the Yoredale rocks only, and has an upthrow to the 

 west. The Butterknowle dyke runs east and west in the county of 

 Durham, and throws the strata down to the south. The Tees Yalley 

 fault is an upthrow of about 45 fathoms to the west. 



The mining country occupies about 400 square miles, and includes 

 the district of the head waters of the Tyne, Wear, and the Tees ; the 

 chief lead district comprising Derwent, East and West Allendale, in 

 Northumberland ; Weardale and Teesdale, in Durham ; and Alston 

 Moor in Cumberland. The geological formation is the Yoredale 

 series, or Mountain Limestone of Phillips, while the lead veins 

 further west in Cumberland are found in the Silurian and meta- 

 morphosed rocks, each district having a somewhat distinct associa- 

 tion of minerals. Discussing the question, What is a vein ? it is 

 worthy of remark that the rich or right-running veins run a little 

 north of east and south of west, the cross-veins bear nearly north 

 and south, besides which are quarter-point veins bearing between 

 the two. When three veins lie near each other the two outer veins 

 are termed north and sun veins respectively. The same vein has 



