I 



After au interval of one mile, where outcrops are 

 wanting, we come to an«»th-r I exposures extending 



over one mile, with well-developed ophitic structure, as 



jpt that the rock is 

 banded This results from the i : that the a 

 scribed irregularii: grain and composition are no 



xhibited in s] ts, 1 ut in long undulatin. 

 into which the former are drawn - lesci ibed by 



H. Williams, in the ssage quoted on } _ 

 Farther down stream these strip.-- 

 almost parallel bat the rock exhil; 



net strike, while at the same time the ophitic structure 

 gradually se where rock 



of undoubted eruptive origin perfectly n 1 with a 



well-developed ophitic structure gradually changes into a 

 striped rock, the Vended structure being produced by 

 variations, not only in the _: tins, but in the 



relative proportion of the eonstitue: its 



This se banding, which is a common structure in 



many parte : ertain anorthosite - formerly 



1 indication of imperfect bedding. But 



from the above-mentioned facts Li is evident that it was 



ibly produce - in a granular, enr 



The next question which presents it whether this 



structure originated in a movement before the rock 

 completely crystallized, or whether it was developed after 

 iidation. In the exposure ar a aribed, : 



found, by repeated and careful study in the field, 

 which point to a movement while the rock was in a 

 molten state. The irregularity in the :he grail 



of prima; _ ;i. and - rtamly not produced 



ssure. The stripes or irregular bands do not assume 

 a definite direction from the start, but wind about at 

 as if the mass had moved when in a pasty condition, and 

 only became niore evenly arranged when, for some re 

 the movement was determined in a definite direction. 



