508 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



The invention of these many new formation names is intended to facilitate 

 correlation along the Boundary; it is hoped that they may be of service to 

 geologists who, in the future, need to correlate with any of the rock-groups 

 cropping out along the Forty-ninth Parallel. 



stratified formations. 



Hozomeen Series. 



A group of rocks believed to belong to the Hozomeen series covers three 

 or more square miles of the Boundary belt north of Glacier Peak and just east 

 of the main divide of the Skagit range. The area presented no geological 

 features of special novelty and its description may.be given in few words. 



The cherty quartzite is here the prevailing rock, occurring generally in 

 thin, flaggy beds from one inch or less to three inches in thickness. Phyllitic 

 interbeds are commoner here than at Mt. Hozomeen. Near the Custer batho- 

 lith, the quartzites are micaceous and the once-argillaceous beds are now mica 

 schists. Occasional bands of probably conformable and extrusive green&tonas 

 are intercalated, but greenstone nowhere in this area assumes the importance 

 it has east of the Skagit river. ISTo limestone was observed in the main area; 

 a patch of intensely metamorphosed schist and quartzite with included limestone 

 pods occurs on the ridge-summit north of Depot creek, where the older Custer 

 granite makes contact with the Chilliwack granodiorite. This stratified mass 

 formed part of the roof of the older batholith and then a second time under- 

 went metamorphism as it was invaded by the Chilliwack batholith. The lime- 

 stone will be described in the section dealing with the contact-aureole about 

 tbe latter intrusive. 



At all the outcrops in the western areas the quartzite-phyllite series has 

 steep dips, ranging from 70° to 90°. In the larger area the beds are intensely 

 crumpled but the strike averages about N. 35° W, ; the dip is generally about 

 vertical. It is probable that several thousand feet of the sedimentary beds 

 alone are represented in this area but it has proved so far impossible to secure 

 either top or bottom for the series. 



Chilliwack Series. 



General Character and Distribution,. — Prom the western limit of the Chilli- 

 wack granodiorite batholith to a point about two miles below the confluence of 

 Tamihy creek, — a distance of sixteen miles in an air-line — , the Chilliwack river 

 flows over a great thickness of sedimentary rocks to which the name, Chilliwack 

 series, has been given. These rocks cover the whole width of the Boundary 

 belt (as mapped) throughout most of the distance and extend far to north and 

 south of the belt. They were examined by Bauerman in his reconnaissance 

 of 1859, when he estimated the total thickness of the sediments exposed along 



