76 GEOLOGICAL SURVEY OF WISCONSIN. 



sions in the drift are partly filled with water, forming lakelets without 

 inlet or outlet. Some of these little lakes are large enough to be kept 

 pure by the action of the winds and waves. The soil is sandy and 

 barren, supporting only a stinted growth of "jack" pines and " scrub 

 oaks." Fire has killed the timber over wide areas, on which grass 

 was growing, exhibiting before our eyes nature's simple method of 

 converting woodland into prairie. The reverse process is just as 

 simple. When prairies are no longer swept over by fire, timber 

 springs up, reconverting prairie into woodland. Grass, with fire as 

 an ally, can beat timber. Timber can beat grass when it has no fire 

 to fight. 



The same kind of "Jack" pine barrens, interspersed with prairie, 

 extends from a short distance above St. Croix Falls to the basin of Lake 

 Superior. Along the streams, on the "bottom" lands, there is a 

 heavy growth of timber, including white pine, oak, poplar, and maple. 

 Towards the sources .of the streams flowing into the St. Croix from 

 the Wisconsin side, are many fine forests, supplying vast quantities 

 of lumber. In the basin of Lake Superior, the soil is fertile, support- 

 ing great forests of Norway pine, some white pine, hemlock, maple, 

 etc. The agricultural capabilities of the St. Croix valley are not very 

 great. The farmer could look to the basin of Lake Superior much 

 more hopefully for a reward of industry and enterprise. 



A new geological " section " of the Penokee range was made by the 

 party at Penokee Gap, along Bad river, where the Wisconsin Central 

 railroad crosses. For a clear description of the structure of this Hu- 

 ronian formation, your excellency is referred to the special report of 

 Charles E. Wright and the accompanying chart. 



In the most conclusive manner, the unconformabitity of the overly- 

 ing northward dipping Huronian, to the underlying southward dipping 

 Laurentian, is made out. 



The undersigned is less reserved than Mr. Wright in expressing an 

 opinion as to the value of the iron deposit in the Penokee range. 

 Careful chemical analyses of good specimens of magnetic ore show 

 that it is very rich in metallic iron, that it is free from titanic acid, 

 that it contains very little phosphorus, that silica is not sufficiently 

 abundant to seriously interfere with its reduction in the furnace. 



Well selected specimens have shown from sixty to sixty-eight per 

 cent, of iron, of fine quality. To scientists it is not necessary to state 

 that the richest possible iron ore is a pure magnetite which yields 

 seventy-two and forty-one hundredths per cent, of metal. It is sim- 

 ply a popular delusion that there are ores rich enough to yield sev- 

 enty-five, eighty or eighty-five per cent, of iron . 



