BLUE EARTH COUNTY. 427 



Jordan sandstone.] 



down a few rods, there is a perpendicular fall of about fourteen feet, which in time of high watei 

 must make a handsome cascade, similar to the Minneopa waterfall. The immediate cause of the 

 fall is the occurrence of a layer of about a foot with a harder or more emluring cement, underlain 

 by crumbling sandstone The alternation of layers here is as follows: 



No. 1. Closely cemented sandstone, projecting beyond the next 5 inches. 



No. '2. Coarse white sand, in water-worn grains, crumbling out easily 6 inches. 



No. 3. Same as No. 1 6 inches. 



No. 4. Same as No. 2 1 foot. 



No. 5. Brink of falls. Same as No. 1 1 foot. 



No. 6. Same as No. 2, seen 30 feet. 



"This horizon is undoubtedly the same as that at Minneopa falls. The appearance of the 

 gorge below the falls, and the occurrence of a cemented part giving rise to the perpendicular fall 

 of the water, are very much the same. The beds lie here, as there, nearly horizontal. The grains 

 of sand are, perhaps, somewhat coarser here than at Minneopa. 



"This sandstone can be seen in the bluffs on the opposite side of the Minnesota river, sur- 

 mounted by a great thickness of drift. The bluffs are mainly wooded, but some^smooth but- 

 tresses and slopes, wrought apparently in the drift, and covered with grass, yet reveal the stone, 

 large slabs and blocks from which lie on the hillside." 



The top of this sandstone in the foregoing section is approximately 100 feet above the river 

 and 860 feet above the sea. About 50 feet below this is the highest outcrop of the St. Lawrence 

 limestone, and this is probably very near the hight of the line of junction of these formations. 

 East from Minneopa falls the Jordan sandstone has a slight dip eastward, and in one and a half 

 miles sinks to a hight only 65 feet above the river, or 820 feet above the sea, at David P. Davis' 

 quarry in South Bend, where the southeast end of its terrace before described (page 426) shows a 

 vertical exposure of 20 feet, from 65 to 85 feet above the river, of the overlying Shakopee 

 limestone. Only the upper one or two feet of the sandstone is exposed, seen at- nearly the same 

 hight with the railroad track and on each side of it, at this quarry. At the former South Bend 

 station, a quarter of a mile farther east, the top of the Jordan sandstone and its junction with 

 this limestone is three feet above the railroad, 55 feet above low water in the river, and 8 1 1 feet 

 above the sea. 



A mile farther east, at the highway bridge crossing Blue Earth river, the line of junction of 

 these formations is 40 feet, very nearly, above low water of the Minnesota river. At the quarries 

 and lime-kilns in the north part of Mankato, this line is about 10 feet above low water, the river 

 at this stage being there 750 feet above the sea. About a mile and three-quarters below Man- 

 kato, at a point on the river sometimes known as "Hurricane bend," in section 36 of Lime town- 

 ship, the Jordan sandstone reaches 45 feet above the river, being overlain by the Shakopee lime- 

 stone. 



The thickness of the Jordan sandstone in Blue Earth county appears to be about 75 feet 

 In the section of the deep well at Mankato, this formation was absent, having been wholly re- 

 moved, with perhaps some of the underlying St. Lawrence limestone, by pre-glacial erosion. The 

 top of this sandstone at its most western outcrops, in Judson and at Minneopa, has a hight above 

 the sea of 860 or 865 feet, while a half dozen miles eastward in Mankato and Lime, its top is at 

 760 to 790 feet. The dip eastward thus averages twelve or fifteen feet per mile, but in some por- 

 tions, as from Minneopa to South Bend, it is as much as thirty feet to the mile, or about a third 

 of a degree. 



Along the Blue Earth river the Jordan sandstone and the overlying Shakopee limestone are 

 seen at many places in the two and a half miles below the mouth of the LeSueur river; and 

 above this point these strata are frequently seen in the bluffs of the Blue Earth river along a dis- 

 tance of two miles from the new bridge in section 27, South Bend, westward to the N. W. J of 

 section 29. The course of the river in this distance passes about one mile south of Minneopa falls. 

 Farther up the Blue Earth river no outcrops of the Shakopee limestone are found, but this sand- 

 stone continues in exposures in the lower part of the bluffs, being in sight and forming vertical 

 banks on one side or the other along nearly the entire extent of four and a half miles, measured 

 in a straight line, to the N. E. } of section 13, Garden City, ending near the former site of Cap- 

 pel's mill, half a mile below the mouth of the Watonwan river. In the two miles above the new 



