TOPOGRAPHY OF KEWEENAW POINT. 165 
north side of this last ridge is again a gradual slope to the lake, which is 
reached at seven miles. All of these ridges, save the Bohemian, or southern- 
most, which presents a rounded contour, show the same structure, viz, a 
steep, often cliff-like, southern face, and a gradual northern slope, coin- 
ciding more or less with the dip of the strata. 
East of the line of profile just described these ridges continue well 
marked, some of them quite to the end of the point. Curving to the south- 
ward with the strata the more southerly ranges reach the lake soonest on the 
south side of the point. Westward also the same ridge structure continues 
well marked to beyond Eagle River, or well around the southwestern turn 
in the trend of the point. The most northern of the ridges named die out 
soonest, to the westward, running into the lake between Agate and Eagle 
Harbors; whence, for some miles westward, the trends of the strata and of 
the coast line make small angles with each other in such a manner that suc- 
cessively lower layers appear on the shore as it is followed westward. The 
Greenstone Range lasts the longest of the four, running as far west as 
Gratiot River. 
Beyond Gratiot River the several ridges all merge into one broad swell, 
witha steep southeastern slope facing the eastern lowland, and aflat northwest- 
ern slope towards Lake Superior. As Portage Lake is approached the north- 
western slope grows broader and flatter, until in the neighborhood of that 
lake there is a western as well as an eastern lowland, with this prominent 
difference, that the eastern lowland ends abruptly against the central ridge, 
while that on the west merges gradually into it. The same conditions con- 
tinue to the westward as far as the Porcupine Mountains, viz: a low area 
bordering the lake, reaching ten or twelve miles in width, which merges 
southward into a high ridge, which again presents towards a southern low- 
land a bold south-facing cliff. 
All of the topographical features thus described result directly from the 
underlying rock structure. 
The abrupt break between the eastern or southern lowland and the 
central ridge is the junction line between a flat-lying sandstone and an older 
series of northward-dipping resistant crystalline rocks of great aggregate 
thickness. This line marks also the course of a great fault. The west- 
