THE KITCrir SCHISTS. 107 



the little chlorite rods are arrangeil likt'wisc witli tlieii- loiiL;cr axes in the 

 same direction, and the lenticular areas of the mineral arc ehmiifatfil in 

 the same way. Arotmd the fragments, large and small, the lamina' of 

 chlorite and sericite bend, and occasionally one ot' the lai-gei- grains of the 

 inosai(! matrix exhibits nndnlatorv extinction. These are tlie only evidences 

 of the action of pressure within the schists, but they are sutticient to show 

 that the rocks have suffered mashing. AYliere the scliistosity is gj-eatest 

 the quantitv of chlorite and sericite present in the rock is g-reatest; where 

 the foliation is scarceh- discernible there may be ])resent much chlorite, 

 but little sericite. 



In addition to the tufil'aceous scliists in the Kitclii formation, there are 

 others in which no fragmental material can be detected. In the field these 

 rocks Avere taken for the more massive phases of the tuffaceous schists. 

 Under the microscope, however, a difference in the stnu-ture of the rocks 

 is detected. The feldspars of the nontuffaceons bauds are in crystals, and 

 uot in fragments of crystals, and the association of feldsjiar and chlorite 

 a])2)roaches the ophitic association of the plagioclase and augite in diabase, 

 or the association of feldspar laths and glass in certain feldsj)athic basalts. 

 In composition the fragmental and the nonfragmental schists are identical. 

 In all probability these Ijands i-epresent the lava flows or sheets that accom- 

 panied the extravasation and deposition f>f the tuffs. Whethei- they A\-ere 

 surface flows or intrusive sheets can not now be told, for all the tiner detail 

 of their structure has disajijjeared. 



ACID SCIIIST.S. 



The sericite-schists — most abundantly developed on the south side of 

 the Kitchi area, in contact with the Marcpiette beds, l)ut occurring also 

 elsewhere, interbedded with the basic schists — in thin section are essentially 

 similar to the green schistose rocks interbedded with the conglomerates. 

 They differ principally in having the sericite, rather than the chlorite, as 

 their principal micaceous component. Many of these light-colored schists 

 are composed almost exclusively of sericite and (piartz, but most of them 

 contain chlorite also. By increase in the pro})ortion of chlorite in them 

 they pass gradually into the green tuff's. 



