PLATE LV. 



PINE COUNTY, 1888. WARREN UPHAM. 



The Archean is found in the northwestern corner of this county, but wholly west 

 of Kettle river. It consists of mica schist, often conspicuously veined with white 

 quartz, rising in rough knobs forty to seventy-five feet high. This is west and north- 

 west from Sturgeon Lake station. About ten miles further southwest, namely, in 

 the southeast corner of sec. 30, T. 44-21, is found a gneissoid granite. This also 

 appears in the north part of section 29, while, within half a mile still further north- 

 east, in the valley of the creek, is sandstone. It is evident that there is an overlap- 

 ping nonconformity of the latter upon the Archean. The sandstone is probably the 

 same as that seen at Hinckley and widely in the Kettle River valley, supposed to 

 belong to the Upper Cambrian. The same sandstone is seen in the Little Willow 

 river, sees. 1 and 2, T. 44-19, extending half a mile, rising ten feet above the river. 

 This sandstone forms almost continuous exposure along the Kettle river from the 

 north line of town 43 to within two miles of the southern line of town 41, where it 

 is abruptly replaced by trap for an interval of about two miles. It reappears, how- 

 ever, in town 40, and also along the St. Croix river in Chengwatana and Pine City 

 townships. It has been called the Hinckley sandstone, from Hinckley, in this county, 

 where it was formerly quarried. It overlies the traps nonconformably but underlies 

 conformably the sandstone and impure limestone which themselves come upon the 

 the trap at Taylor's Palls. This shows a gradual sinking of the region below the 

 ocean during the accumulation of the Hinckley and St. Croix sandstones, which was 

 earliest, and probably greatest, toward the north. Whether the trap seen on the 

 Snake river at Chengwatana and on the Kettle river at its union with the St. Croix, 







dipping eastwardly, belongs to the eruptive epoch of the Cabotian or the Manitou, is 

 not known. 



This trap, with its surface amygdaloids and its conglomerates of red felsyte and 

 quartz-porphyry,* is very thick, containing traces of metallic copper, and most prob- 

 ably belongs to the series that appears at Duluth and eastward, which is Cabotian, 

 i. e., it is probably older than the Puckwunge conglomerate, and is represented in the 

 section at Duluth by No. 4 of the summary statement of the Short Line Park deep 

 well, page 570 of volume IV. It is also probable that the Hinckley sandstone, at 

 points further east and northeast, where locally the traps are wanting, passes con- 

 formably downward into the red sandstones of Fond du Lac, which are interbedded 

 with much red shale. Such shale is the effect of cotemporary volcanic eruption of 

 the Manitou igneous epoch. 



*The most northern point at which these rocks are known in this county is in the north part of sec. 25, T. 45-17, nearly on 

 the divide between the highest sources of the Willow river and thc_' Nemadji. 



