FILLMOKE COUNTY. 285 



Jordan and Shakopee.] 



in the Minnesota valley. It seems to vary from twenty-five i'eet to forty 

 feet. It is uniformly a coarse-grained quartzose, crumbling and light-col- 

 ored sandstone. It is sometimes locally stained with iron from surface 

 water, when it presents a reddish or rusty color, and is apt to be much 

 harder. It has in _such cases a shell or thin coating of harder rock about 

 half an inch in thickness on the weathered surfaces, on penetrating which 

 the grains are loosely cemented and even crumbling. In other places it 

 presents internally a streaked appearance, due to the stoppage of iron fil- 

 tering through its strata. No fossils have been found in it in this county. 



One of the best exposures for examining this sandstone may be seen at 

 Preston, where it rises twenty-five feet above the level of the river opposite 

 the stone mill, and is surmounted by about thirty-five feet of the Shakopee 

 limestone. The bluff itself rises about ninety-five feet above the river, but 

 the contents of the upper portion, though probably of the Shakopee, are not 

 certainly known. The loam covers it. The bedding of the stone here'is 

 regular, though in some places a little wavy, and is of all thicknesses from 

 a foot to three or four inches. 



At Lanesboro the Jordan exhibits, near the top, a finely concretionary 

 structure. The balls vary from a few inches to nearly a" foot in diameter. 

 Some of them are elongated, and several are frequently united. The rock 

 itself is generally friable and crumbles out, leaving the concretionary shapes 

 visible. They are often loosened and roll down the bluff. They lie in 

 approximate layers for a thickness of four or five feet. Some of them are 

 pendant from the projecting shelf, and stud the whole under surface. They 

 are generally spherical, but when they are lengthened perpendicularly they 

 show the original lamination that ran through the rock, in the form of rings 

 and furrows. 



At Clear Grit the Jordan is twenty-five feet thick, and is exceedingly 

 ferruginous. At Lanesboro it is about forty feet thick. 



The Shakopee limestone. This is so named from the village of Shakopee 

 in Scott county, on the Minnesota river, where it was first identified as a 

 distinct member of the great Lower Magnesian formation of Dr. Owen.* 

 In Fillmore county it is more frequently seen along the valley of Root river 



*Dr. Owen's detailed descriptions apply the name Lower Magrnesian to the St. Lawrence limestone, and Dr, Shu- 

 mard's to the Shakopee, as these limestones were regarded as one. Wherever they saw the Jordan sandstone they inis- 

 teok it either for the St. Peter or the St. Croix, though in the latter ease supposing it to be of the age of the Potsdam. 



