ON ST. LOUIS RIVER. 



307 



reconnoissaiico will be given in another Section. It was finished on the 30th of 

 July ; and on the 31st, I proceeded to La Pointe, to procure provisions for the 

 remainder of the season. During my absence, Colonel Whittlesey explored Amine- 

 kan and Poplar Rivers. I reached St. Louis River on the 9th, and on the 12th 

 we began our explorations on that stream. 



4. St. Louis River, from Fond du Lac to the Mouth of Upper Embarras River. — A 

 short distance above the village of Fond du Lac, an exposure of sandstone, ten feet 

 in thickness, is seen on the left bank of the river, overlaid by a very heavy deposit 

 of sand, clay, and red marl. The upper beds are thick and compact, the lower ones 

 shaly, and contain numerous small pebbles at the partings. As the river is ascended, 

 the rocks rapidly increase to sixty-five feet in thickness, and dip to the southeast 

 7°. Nearly three miles above the village, following the bends of the river, the 

 sandstone is found to rest on conglomerate, and this last-named rock on shales and 

 slates. The deposits up to this point, in descending order, are : 



1. Red sandy marl. 



2. Red clay-beds — stratified and indurated, with boulders in the upper part, and dipping with the sand- 

 stones. 



3. Gray sandstone, alternating with white, red, and mottled beds, in layers from one to throe feet thick. 



4. Shaly sandstone, with hard seams. 



5. Very light gray sandstone, of a reddish tint, with numerous casts of shrinkage cracks on the 

 under surface of one of the beds, and covered with scales of mica. (No. 438.) 



6. Dark reddish-brown shale, with alternations of thin beds of hard, argillaceous sandstone, which 

 exhibit on the upper surface numerous rounded elongated eminences, which have sometimes been called 

 " mud drops." (Nos. 443 and 444.) 



7. Light reddish-gray sandstones and shales. (No. 445.) 



8. Thin beds of siliceous shale and pebbly sandstone, alternating with dark red, ripple-marked beds. 

 (No. 446.) 



9. Siliceous shale, with seams of small pebbles- (No. 447.) 



10. Fine conglomerate. (No. 442.) 



11. Red shaly sandstone — like No. 447. 



12. Greenish-gray sandy schist. 



13. Coarse quartzose conglomerate. (No. 441.) 



The dip of the sandstones and siliceous shales, and the upper conglomerate (No. 

 442), is to the southeast, at an angle varying from G° to 7°. About half a mile 

 above the junction of the overlying beds with the coarse conglomerate (No. 441), 

 is an exceedingly interesting point, the conglomerate being suddenly elevated at an 

 angle of 18°, and exposing the lower shales and slates, upon which the upper rocks 

 rest unconformably. At this place is exposed, in one view, the junction of the 

 slates with the conglomerate, together with the overlying siliceous shale, fine-grained 

 conglomerate, and sandstone beds. (See " Section from the mouth of Upper Piunette 

 River to Rainy Lake" on PI. 2, N.) The most elevated point of the arch of uplift, 

 which bends regularly to the water on each side of the axis, is twenty-five feet 

 above the water-level, the arc or span being about four hundred yards. At one 

 point, the conglomerate fills a fissure, with vertical walls, and several feet in width, 

 in the overlying siliceous shale, and appears to have been thrust up from below like 



