44 WILLIAM J. MILLER 



very sharp contacts against the aplite. This silexite resulted from 

 differentiation practically in the place where it now occurs. 



On the eastern summit of Howard Mountain an aplite dike 

 about one foot wide lies parallel to the foliation of and grades into 

 the coarse granite on one side, but it has a fairly sharp contact 

 on the other, this latter contact evidently being a result of some 

 magmatic flowage along the border of the aplite after its develop- 

 ment. 



On the hill one and one-half miles southwest of Sugarbush 

 post-ofhce a distinctly foliated aplite dike with a maximum width 

 of fifteen feet and traceable for one hundred feet pinches out at one 

 end and everywhere grades into the coarse granite within an inch. 



At the top of Averill Peak a number of aplite dikes up to one 

 foot wide lie in the coarse granite parallel to its foliation and 

 without sharp contacts. Some ordinary pegmatites of the late 

 series cut right across these aplites. Several aplite masses ten to 

 twenty feet long occur as lenses without very sharp contacts against 

 the granite. 



On a spur of Lyon Mountain one mile east-southeast of its 

 summit a number of aplite dikes from one to two feet wide mostly 

 lie roughly parallel to the foliation of the coarse granite, but some 

 cut across at various angles. These dikes carry some dark minerals, 

 are without sharp contacts against the granite, and are usually 

 foliated parallel to their borders. Several of them contain distinct 

 inclusions of the coarse granite in the form of lenses one or two 

 feet long, without sharp contacts against the aplite and parallel 

 to its foliation. The granite must have been almost or quite 

 solidified before the aplitic magma entered. 



One-half mile north of the last-named locality one small aplite 

 dike cuts another without sharp contacts against either aplite or 

 coarse granite. Thus there were two distinct intrusions of aplite 

 not far apart in time. 



Conclusions regarding pegmatite, silexite, and aplite in the gran- 

 ites. — Some of the main conclusions from the foregoing observations 

 are as follows: 



I. The Lyon Mountain granite and the Hawkeye granite are 

 believed to have developed from a single body of intruding magma. 



