108 
EFFECTS OF 
Swaledale is nearly parallel to the Auldgang and other east and west 
lead veins, a small fault perhaps passes down Wensleydale, a remarka- 
ble dislocation ranges east and west along the head waters of the 
Nid, and a great depression about Pateley invites its course afterwards 
to the south-east. But the upper parts of Wharf edale and Ribblesdale 
appear wholly independent of this kind of influence, and in their 
further progress they hold their courses across the lines of disturbance. 
The dislocations in Teesdale are perhaps the most remarkable and 
well traced of those which occur in the mountain limestone district 
of Yorkshire. The Burtree ford dyke, which passes from the head 
of Weardale in Durham by Langdon common and east of Cronkley 
scar, causes in the northern part of its course, according to Mr. Forster, 
a downthrow of eighty fathoms to the east: by my measures in 1838, 
it seems to be sixty or seventy fathoms along the Aldstone moor 
road : and it is probably nearly as much on the east side of Widdybank 
scar and Cronkley fell ; it is supposed to extend to Lune head. 
The Teesdale fault first noticed by Professor Sedgwick, ranges from 
Eggleston by Lonton as far as the High force, and appears to be as 
much a case of a very steep dip to the north as a real fault ; at least 
such is the probable conclusion from the phenomena visible about 
Unthank, Holwick, and Winch bridge. At Middleton the difference 
of level on opposite sides of the valley appears to be some hundreds 
of feet ; between Winch bridge and Holwick scars about one hun- 
dred feet ; but the beds dipping steeply to the north the final result 
may be doubled or trebled. Its course is not at all clear in the 
upper part of the valley ; it may be conjectured to join the Bur- 
tree ford dyke a few miles above the High force, and on the north 
side of Teesdale. 
Besides these, I think there is another considerable dislocation pass- 
ing north-east and south-west along Maize beck, between Mickle fell 
and Birkdale, not far from Caldron snout, having a downthrow to 
the north-west; there is also a very decided dislocation ranging up 
