258 THE GEOLOGY OF MINNESOTA. 



[St. Croix sandstone. 



apparently siliceous. These beds are in the upper portion of the line of constant rock-exposure in 

 the upper part of the high bluffs of the Whitewater river in Whitewater and Elba townships, and 

 in other places, and sometimes their greater endurance is evinced by a shoulder-like jog in the out- 

 line of the turfed slopes, running near the top of the St. Croix. Twenty-five to thirty feet. 



3. Loose, massive sand, more or less stained with iron, generally turfed over, or covered with 

 timber. In favorable situations this loose sandy rock forms a line of constant exposure, since its 

 face becomes nearly perpendicular; the overlying quartzitic beds protecting it from denudation. 

 The thickness of this member amounts to forty or fifty feet. 



4. Argillaceous and siliceous beds much like No. 1, embracing the quarries at Lake City and 

 at Hokah, generally greenish and often sandy, with remains of trilobites and graptolites. The 

 shaly portion of these beds embraces a large percentage of lime. Thirty to forty feet. 



5. Crumbling sand, about fifty feet. 



6. Shales and shaly sandrock, generally hid, about eighty-five feet. 



7. Sandrock. quarried by Tostevin at Dresbach ; including at least one shale bed of six feet 

 in its lower portion, which is generally spring-bearing along the foot of the bluffs ; 120 to 150 feet. 



8. Shales and shaly sandrock, very fossiliferous ; extending to the water level at Dresbach, 

 and including a conglomerate bed of four inches ; ten to fifteen feet. 



9. Gray sandrock, penetrated by the Winona Mining company at Dresbach below the level 

 of the Mississippi, at least twenty feet. 



10. At Dresbach the Davis brothers drilled for coal(!) a few years ago to the depth of 116 feet 

 below the depot level, and found all the way nothing but shale and shaly. sandrock alternating. 

 Hence, add for Davis' drill, shales aud shaly sandrock below all the above, sixty-eight feet. 

 Total thickness of the St. Croix in Winona county, 488 to 558 feet. 



No. 8, above, contains what may be pteropodous forms, also some that 

 may be orthoceratitic, and fragments of trilobites, and numerous specimens 

 of Lingula. One bed of about sixteen inches at Dresbach, is largely made 

 up of linguloid shells. It is fragile. The shales, which are bluish, contain 

 numerous beautiful specimens of mud-cracks, and of stems of fucoids. The 

 conglomerate, which is in No. 8, is composed of fossiliferous pebbles of a 

 gray sandstone, which is apparently only hardened pieces of rock like No. 9, 

 or like No. 7, and is almost quartzyte, showing some mica-scales. 



At Beaver, the St. Croix sandstone rises about 300 feet above the river 

 and at Stockton it rises 190 feet above the depot, which is 113 feet above 

 above low water at Winona, giving 303 feet for the thickness of the St. 

 Croix, as exposed at Winona and Stockton, exclusive of any dip in the 

 formation, which cannot amount to more than twenty-five feet. 



At Winona, about half a mile above the foot of Observatory bluff, at 

 the base of the bluffs, may be seen a much rusted and hardened sandstone, 

 heavy and massive, the bottom of the exposure being about fifteen feet 

 above the surface of Winona lake. This contains numerous specimens of a 

 species of Lingula. 



The location of the shaft of the Winona County Mining Company is in 

 the north part of the village of Dresbach, at the level of the Mississippi, 



