460 

 QUATERNARY. 



LOWER 



SILURIAN. 



AECH^AN. 



GEOLOGY OF CENTRAL WISCONSIN. 



Recent Peat beds; bog iron ores. 



Champlain Lacustrine clays, over 200 feet thick. 



Glacial " Drift"; including bowlders, till, sand, gravel, etc. 



C Galena limestone; dolomite, 300 to 350 feet. 

 Trenton. ~{ Trenton limestone; alternating limestones and 

 [ dolomites; in all 100 to 120 feet. 



{St. Peters sandstone; 15 to 120 feet. 

 Lower Magnesian limestone; dolomite, 50 to 

 125 feet. 



J Madison sandstone beds, 35 

 to 50 feet. 



Mendota limestone beds, 30 

 to 45 feet. 



Including possibly two dis- 

 Primordial. ~{ kinck formations, the one 



lying upon the eroded sur- 

 Lower or Pots- j face of the other; in all 800 

 dam sandstone. ' to 1000 feet thick, but vary- 

 ing much on account of the 

 irregular surface of the un- 

 derlying rocks. 



{Quartzites, schists, quartz-porphyries, silicious 

 iron ores, gneiss (?); many thousand feet 

 thick. 



C Gneiss, granite, schist, diorite, quartzite, etc.; 

 Laurentian. < no crystalline limestone; many thousand feet 

 thick. 



