50 THE PENOKEE IRON BEAEINCx SERIES. 



A variation in thc' degree of uortheily dip of tlie beds of the Hurouiau has also 

 very measurably affected the surface features. From a in)iut on the ridge a few 

 miles west of Bad river to the Montreal the augle of dip is always very high, 55° to 

 I'yo, wliile farther west it lessens to 45'=, 3.5°, 25°, and even to 20° or 15o. In these 

 places the result is a longer front slope to the ridge, and a very steep, fre<iueiitly bold 

 and jirecipitous southern face, imide up usually of heavily bedded (piartzitic; iron ore 

 overlying the siliceous schist, which now loses its jiromiuence and foiras only the foot 

 of the southern face. Tlie entire absence of the Penokee range in T. 44, R. 4 W. is 

 perhaps to be attributed in part to a lessening in dip, though probably chiefly to a 

 change in the character of the lower layers of the series. (Pp. 101-103). 



The Huronian series consists of a succession of more or less highly schistose to 

 slaty Iteds, which reacli a total thickness in the widest part of nearly 13,000 feet. 

 These layers all stand inclined at a high angle to the north, and stretch across the 

 country in outcrops generally parallel to the southern limit of the formation, some of 

 the more prominent ones preserving their characters across the whole width of the 

 district, a distance of about 45 miles. Inclining, as they always do, to the north, 

 these beds are without folds, and the series is only limited in that direction by the 

 overlapping of masses of igneous rocks belonging to an unconformable system — 

 the Copper-bearing or Keweenawau series — the unconformity being one, however, 

 recognizable only on a comprehensive survey of the region, and not by any observed 

 contact between the two formations. The absence of any folds in so highly altered 

 and inclined strata is easily explained, if we regard them as forming part of a great 

 bend underneath the trough of Lake Superior and reappearing on the north side of 

 the lake with a reversed inclination. These points have been brought out on a prev- 

 ious page, and need only to be alluded to here. 



The degree of northward inclination of the Huronian beds is, for most of the 

 course of the formation, from 5.5° to 75°; most usually between 65° and 75°. To the 

 west of Sec. 16, T. 44, R. 3 W., however, the degree of inclination is nearly always 

 much less, becoming at times as low as 20°. The bends in the course of the forma- 

 tion have already been noted in a general way. Some of these are exceedingly abrupt, 

 as, for instance, on Sec. 10, T. 44, R. 2 W. ; at the crossing of the creek in sections 8 

 and 17, T. 44, R. 2 W., and at several places in the western extension of the formation. 

 These bends are well marked out in the rock exposures and are noted in detail on the 

 accompanying maps. 



At the passage of Bad river, the strata are crossed by a fault, trending about 

 N. 17° W., the layers on the west side of the fault being thrown SOO feet to the north- 

 ward of those on the east side; or, regarding the throw as a vei'tical one, the western 

 side has been elevated or the eastern depressed a vertical distance of over 1,700 feet; 

 the apparent lateral throw, on this supposition, being explained by the inclined posi- 

 tion of the strata. This fault is marked in the topography by a corresponding setoff 



