2 GEORGE V. SESSIONAL PAPER No. 25a A. 1912 



CHAPTER XVII. 



FORMATIONS OF THE HOZOMEEN RANGE. 



General Description. 



As the section is carried westward across the Pasayten river, we enter a 

 new and more or less distinct geological province. One natural western limit 

 of this province occurs at Lightning creek, but it is convenient to describe in 

 the same connection the formations extending a few miles still farther west, so 

 as to group within this chapter the various facts known about the geology of 

 the Hozomeen range. At the Skagit river there is another abrupt change of 

 formations. The Hozomeen range at the Forty-ninth Parallel is, in fact, an 

 unusually well defined mountain group both in its topographic and its structural 

 relations. (Maps No. 14 and 15). 



Within the limits of the Boundary belt the range is composed of a dominant 

 sedimentary group of rocks, here called the ' Pasayten series ' ; a more sub- 

 ordinate, older group of sediments and greenstones, here named the ' Hozomeen 

 series ' ; a volcanic member of the Pasayten series, here named the ' Pasayten 

 Volcanic formation ' ; two small stock-like bodies of ' Lightning Creek diorite,' 

 which cuts the Pasayten series; a larger, typical stock of 'Castle Peak grano- 

 diorite,' also cutting the Pasayten series; a chonolith of syenite porphyry, cut- 

 ting the Pasayten series and probably satellitic from the larger stock; and a 

 few sills and dikes of porphyrite, cutting the Pasayten series and perhaps satel- 

 litic from the Lightning Creek diorite. West of the Pasayten river a small area 

 of the Rem m el batholith enters the five-mile belt. This plutonic mass is the 

 local, unconformable basement of the great Pasayten series of rocks. 



The geographical order of the formations as they are encountered in carry- 

 ing the section westward, will be roughly followed in the brief descriptions of 

 this chapter. The oldest rocks, those of the Hozomeen series, crop out only in 

 the ridge of Mount Hozomeen itself and will be considered last of all. 



Pasayten Series. 



Introduction. — From the Pasayten river to Lightning creek at the eastern 

 foot of Mount Hozomeen — a distance of twenty miles — the Boundary belt is 

 underlain by an extraordinarily thick group of sedimentary rocks, here and 

 there punctured by small bodies of intrusive igneous material. These sediments 

 form a large area which was traversed by Russell and by Smith and Calkins 

 during their respective reconnaissances in the state of Washington. During his 

 journey along the Boundary in the years 1859-61, Bauerman crossed an area of 

 stratified rocks which doubtless represents the northern continuation of the 



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