102 



ELEVENTH REPORT. 



UJX-.CXZkZZ 



' '■' ^''':^ '•.!*■ •'.r .'-'■"-■" .-■•-_■ 



Fig. 3. — Illustrating the fovmation of a deposit of Ijog iron ore. 



Fig. 4 — Illustrating the effect of an uplift of the land. The valley.s are deepened and much of the 

 ore bed shown in Fig. 3 has been eroded away and that part which remains is now on a hill. 



Other Similar Deposits ix Wisconsin and Iowa. 



Ores of the type represented l^y the Gihnan and Cady deposits, have been 

 reported from other points in the driftless area of Wisconsin north of the 

 Wisconsin river. The known deposits are of no commercial importance but 

 it is worthy of note that these occurrences bear the same ]3hysiographic re- 

 lations to valley slopes and upland surfaces as do the Oilman and Cady de- 

 posits. Similar physiographic relations are sho.wn by deposits of similar 

 character in Allamakee county in the northeastern part of Iowa. The largest 

 of these lies directly above the ^'alley of Village Creek near Waukon. It forms 

 a mantle of inconsiderable thickness on the top and upper slopes of Iron hill, 

 the highest hill in the coimty. The other deposits are in similar topographic 

 relations iDut are at different and somewhat lower elevations. According 

 to Calvin,* "at all points mentioned the ore is a comparatively thin veneer 

 lying over the hill top. As already noted the beds of ore that have 

 attracted attention all lie on high points, the highest in the entire county. 

 They are all underlain bv from 50 to 100 feet of Trenton limestone, with the 



*Iowa Geological Survey, Vol , 4, 1895, p 98 et feq. 



