386 THE CRYSTAL FALLS IRON-BEARING DISTRICT. 



outcrops are not especially numerous ; but in the six eastern sections, which 

 include a belt from" a quarter to half a mile wide, a very considerable por- 

 tion of the surface is bare rock. This exceptional degree of exposure has 

 been broug-ht about by the forest fires, which, by loosening the thin soil 

 and destroying the protecting cover of vegetation, have facilitated its 

 removal from the steep-sided knobs that are such characteristic features of 

 the Archean topography. 



TOPOGRAPHY. 



The Archean areas, particularly the southern, are distinguished by 

 a characteristic rougla topography. The surface is exceedingly uneven 

 on rather a small scale, and has already been described as consisting of 

 hummocky elevations alternating with bowl-shaped depressions. Both 

 hummocks and bowls are elongated in an east-and-west direction, in accord- 

 ance with the prevalent gneissic foliation. 



While the surface is thus so full of small details that an adequate 

 delineation of it is the despair of the topographer, the actual relief is 

 insignificant. To men bred on the flat plains of the lower lakes, as were 

 most of the early surveyors and explorers, it may naturally have appeared 

 mountainous, since roughness is a quality particularly noticeable in a wil- 

 derness like this, that can be traveled only on foot. But from a broader 

 point of view the irregularities are almost wholly lost. The higher summits 

 in the same neighborhood rise to within a few feet of each other. The 

 distant sky line is even in all directions. There is, however, a gentle 

 ascent from east to west, quite imperceptible on the ground, and made 

 evident only by the general course of the streams or by leveling. 



Along the contacts between the Archean and Algonkian systems there 

 usualljr but not always exists a topographical depression, occupied by 

 swamp or streams. North of the southern Archean mass this depression 

 is a well-marked linear valley, extending with some interruption from 

 sec. 33, T. 42 N., R. 28 W., on the east, for 6 miles west to sec. 33, T. 42 N., 

 R. 29 W. For 2 miles in tlie middle of this stretch the valley is occupied 

 by the Stm-geon River; thence west for 2 miles by a small feeder of the 

 Sturgeon, while the eastern third holds swamp with ill-defined drainage. 

 On the south the Archean boundary of this valley generally rises with 



