THE GEOLOGIST. 



JUNE 1863. 



KIPPLE-DKIFT IN MICA-SCHIST. 

 Br the Editok. 

 Of all English geologists, Mr. Sorby has been at once the most 

 indefatigable and the most successful in the study of the microscopic 

 structure and metamorphic conditions of rocks. The brief abstract 

 furnished us by the Geological Society, which we print at p. 231, 

 gives but little idea of the importance of the paper Mr. Sorby read 

 last month. It gives, it is true, the pith of the subject, but so 

 short and inexplanatory a paragraph is not likely to attract such at- 

 tention as the paper deserves. Those who have the pleasure of Mr. 

 Sorby's acquaintance know how persistently he works at anything 

 puzzling which comes in his way. He never leaves it until he has 

 got to the solution of the riddle. It happened some time ago, when 

 in Germany, at the meeting of savants at Speyer, on which occa- 

 sion he transmitted an account of the proceedings, with some notes 

 on meteorites and sponges (see Vol. IV. p. 501), that Professor 

 Blum presented him with a specimen of the singular conglomerate 

 known as the " nagcl-llue." This conglomerate, which occurs in 

 some places in Switzerland, consists of hard limestone pebbles, 

 the ends of some being impressed into the substance of others, — 

 a condition hitherto inexplicable, although Blum, Yon Deehen, 

 Eschcr von der Linth, Noggerath, Daubive, and others have 6ssayed 

 opinions and suggestions, some of them attributing the impressions 

 to merely mechanical, others to purely chemical action. In working 

 out this investigation, Mr. Sorby eliminated evidence of a new- 

 phase in the correlation of physical forces ; and in an able and 



VOL. VI. 2 D 



