5 i8 



C. K. LEITH 



DESCENDING SUCCESSION OF FORMATIONS IN THE MARQUETTE, CRYS- 

 TAL FALLS, AND MENOMINEE DISTRICTS. 



CRYSTAL FALLS DIS- MENOMINEE DIS- 



MARQUETTE DISTRICT TR1CT TRICT 



UPPER MARQUETTE UPPER HURONIAN UPPER -MENOMINEE 



1 . Michigamme form- 

 ation, bearing a short 

 distance above its base 

 an iron-bearing horizon, 

 and being replaced in 

 much of the district by 

 the Clarksburg volcanic 

 formation. 



2. Ishpeming forma- 

 tion, being composed of 

 the Goodrich quartzite in 

 the eastern part of the 

 district, and of the Good- 

 rich quartzite and the 

 Bijiki schists in the west- 

 ern part of the district. 



Unconformity 

 LOWER MARQUETTE 



i. Negaunee iron 

 formation, iooo to 1500 

 feet. 



2. Siamo slate, inl 

 places including inter- 

 stratified amygdaloids, 

 200 to 625 feet thick. 



3. Ajibik quartzite, 

 700 to 900 feet. 



1. Michigamme for-") 

 mation, bearing a short 

 distance above its base 

 an iron-bearing horizon. 



1. Great Slate 

 formation. 



2. Quartzite in eastern 

 part of the district. 



H 



J I 



Unconformity 



LOWER HURONIAN 



i. The Groveland 

 formation, about 500 feet 

 thick. 



2. Hemlock volcanic") 

 formation, 1000 to 10,000 

 feet thick. 



In western part of dis- 

 I trict also occupies place 

 of (1) and (3). 



4. Wewe slate, 550 to 

 1050 feet. j 



5. Kona dolomite, 550 

 to 1375 feet. 



6. Mesnard quartzite, 

 100 to 670 feet. 



Unconformity 



3. Mansfield forma- 

 tion, 100 to 1900 feet 



[_ thick. 



4. Randville dolomite, 

 500 to 1500 feet thick. 



5. Sturgeon quartzite, 

 100 to 1000 feet thick. 



Unconformity 



ARCHEAN 



Unconformity 



LOWER MENOMINEE 



i. Vulcan iron 

 formation contain- 

 ing slates. 



2. Antoine dolo- 

 mite. 



3. Sturgeon 

 quartzite. 



Unconformity 



