lo SIDNEY POWERS 



themselves, like the main quartzitic and schistose formations, could have 

 been dissolved. 



Pequawket Mountain, New Hampshire : Pequawket Mountain, 

 the Eastern Kearsarge of New Hampshire, and Moat Mountain, 

 near by, are composed of masses of quartz porphyry, of stock- 

 like form, which contain so many fragments of metamorphic rocks 

 that they have been described as breccias/ The Pequawket mass 

 is about 1,200 feet long and 450 feet wide. It lies at the contact 

 of the older Albany granite and slate. The angular inclusions 

 are very numerous, consisting largely of slates, sandstones, and 

 phyllites, derived from the adjacent terranes. The inclusions do 

 not show any alteration at their contact with the porphyry. The 

 porphyry matrix is vitrophyric in the Pequawket mass, grano- 

 phyric in the Moat mass. As the inclusions do not show as 

 much metamorphism as the surrounding slates, and as the quartz 

 porphyry is not squeezed, Daly concludes that the inclusions have 

 probably come from above the present exposure, where the meta- 

 morphism was not so great. 



Lages, Brazil: Near Lages, Brazil, an inclusion-bearing dike 

 was fovind by Woodworth.^ 



The dike is of trap and was evidently the feeder of one or 

 more of the Triassic trap sheets which are exposed in the Lages 

 area. At the outcrop investigated, the width of the dike is 75 feet. 

 Here the inclusions of foreign rocks constitute one-half of the 

 volume of the dike and comprise red and black shale, coarse- 

 grained basalt, fine-grained basic rock, and amygdaloidal basalt. 

 The fragments of sedimentary rock were apparently disrupted 

 from the walls of the fissure which appears to have been a fault- 

 line. Whether they came from above or below the exposure could 

 not be determined. The amygdaloidal basalt fragments must have 

 come from the overlying Triassic flows according to the deter- 

 mination of the geological structure by Woodworth and others. 

 Furthermore, it is certain that the dike was not formed until after 

 other lavas had been extra vasated and cooled to yield the inclu- 

 sions which sank in the fluid dike-magma. 



' R. A. Daly, Science, N.S., III (1896), 752. 



^J. B. Woodworth, '"Geological Expedition to Brazil and Chile, 1908-9," Bull. 

 Mus. Camp. ZooL, Harvard, LXI, No. i, p. 95. 



