.286 YORKSHIRE NATURALISTS IN UPPER TEESDALE. 



appearance, and more or less parallel with the sedimentary rocks 

 above and below, between which they have been injected. The 

 Whin Sill can be studied in many parts of Northumberland, Durham, 

 and Yorkshire, but in no place to greater advantage than between 

 Middleton-in-Teesdale and Caldron Snout, either in the rugged 

 scars on each side of the river, or in the sections made by the 

 denuding process of the mighty waterfalls of High Force and 

 Caldron Snout. At the latter place the basalt attains its greatest 

 thickness, that is, between 200 ft. and 300 ft., and in the lofty 

 precipices in the vicinity may be seen assuming the columnar 

 structure so characteristic of basalt. 



At the Middleton station conveyances were obtained, as the 

 party had to proceed some eight miles further up the dale before 

 fairly setting to work, passing through the busy little town of 

 Middleton and the hamlets of Newbiggin and Bow Leys ; a short 

 halt was made at the High Force Inn, and at Langdon Beck, a few 

 miles further, they dismounted and crossed over by Widdy Bank to 

 the margin of the river. The scenery had greatly altered as they pro- 

 ceeded — from the broad valley, with its sides dotted with white- 

 washed farmhouses, and here and there fine woods and charming 

 glens, to a bleak and sterile district, with the river slowly gliding 

 along under the shadow of dark and gloomy precipices. The path, 

 too, was excessively rough, reminding one forcibly of the boulder- 

 strewn walk under the cliffs some years ago at Kettleness. On the 

 Yorkshire side were the high basaltic terraces of Cronkley Scars, 

 with masses of debris at their base, and finely displaying the 

 ■ columnar structure alluded to. On the Durham side the tremendous 

 basalt cliffs of Falcon Clints were skirted, and the point was noticed 

 where the heated basalt had come in contact with the underlying 

 limestone (the Melmerby Scar limestone) and had metamorphosed 

 it into a loose granular rock, known generally as 'sugar limestone.' 

 The grains of this are highly crystalline, and have hardly any 

 cohesion with each other, so that it is difficult to obtain a good 

 specimen. On the summit of Cronkley Scars the limestone 

 immediately overlying the basalt, known as the ' Tyne-bottom ' lime- 

 stone, has this granular character from the same cause. Another 

 stretch of arduous walk brought the party to the limit of their 

 journey, the waterfall of Caldron Snout, where the waters of the 

 Tees thunder down jagged terraces of basalt, the foaming cataract 

 being in grand contrast with the black igneous rock. The party 

 ascended the broken sides of the ravine, and crossed the frail-looking 

 plank bridge (nearly 1,500 ft. above the sea-level) into the county 

 of Westmorland, thence immediately crossing over the Maize Beck, 



Naturalist, 



