STUDIES. SCIENTIFIC AND SOCIAL 



Another photograph (Fig. 18) from a negative lent me 

 by Mr. Kendall, shows a boulder of rhomb-porphyry 

 found farther north near the mouth of the Tees, in the 

 boulder-clay of West Rigg, 810 feet above the sea-level. 

 It is one of the characteristic Scandinavian rocks 

 found over a large area round the head of Christiana 

 Fiord, Norway, but nowhere in the British Islands. 



Fig. 18. — a Scandinavian boulder found in Yorkshire. 



Perched Blocks. 



I may here notice one of the many interesting phe- 

 nomena that are only to be explained by ice-carriage, the 

 frequent presence of what are termed perched blocks in all 

 glaciated regions. They consist essentially of masses of 

 rock in positions where they could not have been left by 

 any other agency. The first of these (Fig. 19) is a large 

 and rugged boulder of Silurian shaly rock resting upon 

 carboniferous limestone on the Norber mountain, which 

 forms one of the shoulders of Ingleborough. The distinct- 

 ness of the erratic from the rock on which it rests is well 

 brought out in the photo-print. 



