260 Williams — Conta<tf-me£amorphism near Peekskill. 



I. No. 21. The least altered mica schist from the southern 

 end of Section I. Contains quartz, orthoclase, biotite, mus- 

 covite ; a little oligoclase, tourmaline and zircon. 



II. No. 24. A much crumpled, garnetiferous mica schist, 

 collected north of the road on Section I. 



III. No. 25. Schist from o on Section II. Contains biotite, 

 muscovite, quartz, sillimanite, garnet and very much staurolite. 



IY. No. 37. Schist at the foot of the contact-wall, p. Sec- 

 tion II. Composed of biotite, magnetite, sillimanite, cyanite 

 and garnet. 



It is not intended to imply that the successive layers of the 

 schist may not have differed very materially in their original 

 composition. That such was the case is shown by local varia- 

 tion in the relative proportions of the resultant minerals ; but 

 after allowing for all such differences, there is still a regular 

 and progressive series of changes in the order above indicated. 



Section III. — (q-s on the map.) This section is like the 

 others in showing a gradual and constantly increasing nieta- 

 morphism of the mica schist as we pass from the river bank at 

 q, up the road which winds along the hill about half a mile 

 west of the railroad station. Its main interest, however, is de- 

 rived from the inclusions of the schist within the massive rock 

 itself. These inclusions differ very much in size and character 

 but they exhibit the extremest place of the metamorphic action. 

 The largest inclusions are, as might be expected, nearest to the 

 contact. Here some bands may be traced for a hundred feet 

 or more, as though the molten rock had been forced between 

 the schist strata without greatly displacing them. Farther 

 within the contact line, on the top of the hill above Cruger's 

 Point, many smaller inclusions of various shapes and sizes may 

 be seen. They have been quite fully described by Professor 

 Dana, at least so far as their macroscopic appearance goes.* 



These included schist fragments are of great petrographical 

 interest because of the variety of unusual mineral aggregates 

 which they present. That these minerals are very largely new 

 crystallizations produced by metamorphic action, is in some 

 cases shown by their having an arrangement parallel to the 

 boundaries of the fragment. The accompanying figure repre- 

 sents the banding in an inclusion about live feet long exposed 

 on a glaciated surface of the mica-dorite, just where the road 

 reaches the top of the hill. Toward the right the banding 

 plainly follows the outline of the inclusion. Specimens No. 

 30 and 31 were taken from this inclusion. 



Ascending the line of this section we came first {r on the 

 map) to the exposure of highly contorted schist figured by 

 Professor Dana.f A thin section of this (No. 5), cut across 



* This Journal. Ill, xx, pp. 209-210, Sept. 1880. f Loc. cit. p. 209, fig. 11. 



