Geological Notes on the Middleton-in-Teesdale District. 269 



in the Ingleboroiigh district have become greatly attenuated 

 as we proceed northward, and have been replaced to a con- 

 siderable extent l)v bands of thin limestone, shales and grits. 

 These indicate that considerable earth movements have been 

 in progress in the area, and that the relative position of the 

 Teesdale area of the ancient littoral, and of detritus-bearing 

 streams, had been frequently undergoing change during Yore- 

 dale times, and to a much greater extent than was the case at 

 no great distance to the south. 



The outstanding geological feature of Upper Teesdale is 

 the Great Whin Sill, an enormous intrusive dolerite mass 



Tarns on the undercliff, Cronkley Scars, Upper Teesdale. 



extending into Northumberland, but having its greatest 

 development in Teesdale. It is prominent in precipitous cliffs 

 on the south side of the river from Middleton to High Force. 

 It forms the river bed in many places, and at High Force the 

 river plunges over a lip of the basalt into the gorge, 69 feet 

 below. The outcrop is also well seen in the precipices of 

 Cronkley Scars, Falcon Clints and Cauldron Snout (a cascade 

 of about 200 feet over basalt) where the columnar structure 

 was very evident. 



In Park End quarry it was noticed that coarseness of the 



rgio July I. 



