290 YORKSHIRE NATURALISTS IN UPPER TEESDALE. 



problems presented and the grand geology of the district afford 

 ample room for further study and examination than they could 

 possibly give at the time, but still the experience gained will be 

 an admirable ground-work for another visit. The kindness and 

 cordiality of the good-hearted dalesmen were conspicuous through- 

 out the excursion. Messrs. Wearmouth, Raine, and others, in 

 addition to the leader already alluded to, vied assiduously with 

 each other in giving ample information and rendering valuable 

 services — services of a character to be gratefully appreciated by 

 the members. As the party was scattered throughout the dale, it 

 is impossible to speak of the whole of the accommodation • but 

 those geologists who stayed at 'Ye Cleveland Arms' in Middleton 

 will not easily forget the capital cuisine, the careful attention, and 

 the excellent sleeping quarters — all matters of supreme importance 

 to hungry and weary hammer-men. There was much discussion 

 as to the composition of basalt. The following is an analysis of 

 the Teesdale Whin Sill, made in the laboratory of Dr. Percy. The 

 specimen was taken from Widdy Bank Fell, on the way to Caldron 

 Snout: — Silica, 51*47; alumina, 16*48 • protoxide of iron, 8-49; 

 peroxide of iron, 3*61 • protoxide of manganese, 0*46; lime, 8*22; 

 magnesia, 5*10 • potash, 3-28 ; soda, 1*18 ; iron, o - o8 ; sulphur, 0*09 ; 

 water, 170. 



The great Dr. Adam Sedgwick, whom Yorkshire recognises as 

 one of the most illustrious of her sons, drew attention to the geology 

 of High Teesdale more than sixty years ago, and published an 

 elaborate and learned treatise upon the same. This is now extremely 

 difficult to consult, and therefore a summary of his exhaustive 

 observations may be acceptable. He says, in regard ' to the em- 

 bedded masses of trap (commonly called the Great Whin Sill), it 

 appears that immediately below Caldron Snout they are not parallel 

 to the strata between which they are interposed ; that between Force 

 Garth Hill and Holwick, where the inferior surface of the trap 

 appears to be nearly parallel to the lower strata, the country is inter- 

 sected by numerous fractures which have greatly changed the level 

 of the corresponding parts of the different formations ; that a fracture 

 passes down the valley and produces a great throw which conceals 

 the trap on the north side of the river ; that the trap on the south 

 side of the valley descends among the strata in the form of a great 

 wedge which diminishes in thickness from between 200 ft. and 300 It. 

 to about 12 ft. ; that near the apparent termination of the Whin Sill 

 a mass of trap breaks out on the opposite bank of the Tees, and is 

 probably prolonged in the form of a dyke, or system of dykes, 

 through the eastern moorlands.' 



Naturalist, 



