EXTENT OF THE FAULT 321 



granitic rocks at 2,150 feet, or 1,225 feet below sealevel. Stillwater and 

 Minneapolis are 24 miles apart. 



Thus it is seen that along the north and west sides of this area of 

 diabases and conglomerates there extends a sharp line of demarkation, 

 clearly defining the area in those directions, and at the same time ap- 

 parently separating these rocks as a geographic area from that other area 

 assigned to the same geologic age, beginning near Duluth and extending 

 northeastward beyond the international boundary, and constituting the 

 great northeastern Minnesota area of the Keweenawan series. 



It does not follow from this interpretation — namely, that faulting has 

 been a factor in bringing about the separation of these two areas — that 

 they did not in that earlier time, the days of eruptive activity and con- 

 glomerate building, form parts of one and the same geographic province, 

 nor that they are not now, below the Cambrian, the continuous floor on 

 which this oceanic deposit was laid down. 



Exposures of the Keweenawan 

 eastern pine and carlton counties 



Commencing at the north and on-the very eastern border of Minnesota, 

 we note that the northern edge of the Keweenawan enters the state from 

 Wisconsin, pursuing a southwesterly direction, in section 12, township 

 4, range 1 west. The rocks at this point are covered with drift, but the 

 exposures within comparatively short distances in either direction dis- 

 closed in the channels of the streams enable geologists to locate the 

 plac6 quite accurately. These exposures may be mentioned : Township 

 45, ranges 16 and 17 ; township 44, range 16 ; township 42, range 16, at 

 several localities. The rocks have a southwesterly strike and a strong 

 southeasterly dip. 



TAYLORS FALLS 



At this place and its environs is an interesting succession of lava flows, 

 worked out by Doctor Berkey.* They are a part of the southwest exten- 

 sion of the volcanic flows of the Keweenawan, which are known to occur 

 at Stillwater, at 717 feet below the surface. Structurally, they are a 

 series of lava flows, often columnar in habit, of dark color, mediumly 

 crystalline, and ophitic or porphyritic in texture, frequently both. The 

 flows vary from 30 to 60 feet in thickness, they average 15 degrees in 

 dip to the southwest, and represent a total thickness of nearly 6,000 feet. 

 This does not probably represent the entire Keweenawan at this point. 



*Chas. P. Berkey : Greology of the Saint Croix dalles, Amer. Geologist, vol. xx, 1887, pp. 377-383, 

 XL VI— Bum-. Geol, Soc. Am., Vol. 12, 1900 



