266 0. II. Hershey — Belt and Pelona Series. 



the loss chiefly of the Upper Burke, which I could recognize 

 in the vicinity of Burke, but not near Lower Glidden and 

 Revett lakes. 



The Revett formation at the type section in the cirque walls 

 overlooking Revett Lake consists of heavy-bedded, hard white 

 quartzites alternating with much thinner beds of greenish seri- 

 citic quartzite, of a thickness, west of Lower Glidden Lake and 

 on the west side of Twenty-two Mile Creek, of 1,000 to 1,200 feet. 

 In the Wardner District the series is thicker and the greenish 

 sericitic quartzites form a more important constituent. The 

 Lower Revett is harder and more resistant to weathering than 

 either member of the Burke. Its areas are characterized by 

 a very stony soil, in many places taluses bare of vegetation, in 

 which material there is an angularity .not present in the debris 

 from any other formation. In a good section in Big Creek 

 Valley the thickness is 1,300 feet. The Middle Revett divi- 

 sion is simply the highest prominent band of white, nearly pure 

 quartzite; it is heavy-bedded and cross-bedded, weathers either 

 white or yellowish, and has a habit of outcroppiug as a persist- 

 ent precipitous ledge. It is generally 75 to 100 feet thick, but 

 thins perceptibly in short distances, and may be practically 

 absent from portions of the district. The characteristic rock of 

 the Upper Revett is a rather thin-bedded, greenish, sericitic 

 quartzite, similar to the thinner-bedded portion of the Lower 

 Revett, though near the top it has several white quartzite beds 

 and locally a few thin purplish gray bands ; in fact, it resem- 

 bles the Lower Burke. The thickness is about 900 feet. This 

 gives the Revett formation a thickness of about 2,300 feet in 

 the Wardner District. 



Much of the St. Regis mapped by me in the district is the 

 basal member, a rather hard, thin-bedded quartzite of gray and 

 lavender colors. There is an alternation of green and purple- 

 gray shales and thin-bedded quartzites. No complete section 

 is exposed in the district, but I have adopted Calkins' estimate 

 of 1,000 feet for the Coeur d'Alene District in general. The 

 Wallace formation is confined chiefly to a large block between 

 two great faults, the Osburn and Alhambra, and probably 

 includes nearly all of the 4,000 feet thickness estimated by 

 Calkins for the formation. The lithologic features are similar 

 to those near Wallace and eastward, except that the quartzite 

 beds are thicker and purer and there is less limestone. Although 

 much of the formation is somewhat calcareous, the only lime- 

 stone observed is a thin bed of blue-gray, nearly pure limestone 

 in the Elk Creek basin. The blue-gray argillites weather to 

 an orange color and the quartzites to a light red color. The 

 Striped Peak formation has long since been eroded from all 

 parts of the district. 



