﻿H. C. Lewis — Comparative Studies upon Glaciation. 433 



feet in width, appearing almost like a vein or dike intersecting 

 the trap. In this breccia the trap and sandstone are confusedly 

 mixed together. The appearance is suggestive of a friction 

 breccia;* bat, on closer examination, the structure is seen to be 

 quite different from von Cotta's description of a friction breccia. 

 Here the matrix seems to consist of the material of the red 

 sandstone, while the included pebbles are of trap. The trap 

 fragments, especially the smaller ones, are extensively altered to 

 chlorite. In the immediate vicinity of this breccia, the trap 

 shows joints with slickensides. It would seem as if the forma- 

 tion of this breccia was due to some disturbance subsequent to 

 the outflow and consolidation of trie trap. The breccia may 

 probably be considered to be a u fault-rock.' , t The occurrence 

 of disturbances subsequent to the consolidation of the trap is 

 confirmed by an examination of the more southerly cutting, 

 where two unmistakable faults may be seen. In the southern 

 cutting the contact of the amygdaloid with the overlying sand- 

 stone is exposed ; but the rocks at that point are too much de- 

 composed to afford any satisfactory observations. There seems 

 to be nothing in the phenomena observed in the cuttings on 

 the right bank of the river, which contradicts the evidence of 

 the contemporaneous origin of the trap afforded by the section 

 •on the left bank. 



Wesleyan University, Middletown, Conn , Aug. 13, 1886. 



Art. L. — Comparative Studies upon the Glaciation of North 

 America, Great Britain, and Ire! and ; by Professor H. Car- 

 vill Lewis. (Abstract by the author of a paper read at the 

 Birmingham meeting of the British Association, September, 

 1886.) 



The object of this paper was to show that the glacial deposits 

 of Great Britain and Ireland, like those of America, may be in- 

 terpreted most satisfactorily by considering them with reference 

 to a series of great terminal moraines, which both define conflu- 

 ent lobes of ice, and often mark the line separating the glacia- 

 ted from the non-glaciated areas. 



The paper began with a sketch of recent investigations upon 

 the glaciation of North America, with special reference to the 

 significance of the terminal moraines discovered within the last 

 few years. The principal characters of these moraines were 

 given, and a map was exhibited showing the extent of the gla- 

 ciated area of North America, the course of the interlobate and 



* Von Cotta, Rocks Classified and Described, p. 305. 

 f G-eikie. Text-book of Geology, 2d edition, p. 161. 





