638 THE GEOLOGY OF MINNESOTA. 



[Joidan sandstone and Shakopee limestone. 



we find the cast of a small Orthis, with fine radiating strise, and portions of the cephalothorax of a 

 trilobite, related to the family Olenida." Again, in this limestone at Kasota, Dr. Shumard de- 

 tected "Lingula Dacotaensis, and the remains of a species of trilobite, apparently identical with 

 that occurring at White Rock/' 



An analysis of the Shakopee limestone at Ottawa, given in Dr. Shumard's report, is as fol- 

 lows: 



Carbonate of lime 58.65 



Carbonate of magnesia 29.15 



Insoluble matter 7.25 



Alumina, oxide of iron, and manganese 1.55 



Water 2.65 



Loss 0.75 



100.00 



Analyses of this limestone in Kasota, made by Prof. S. F. Peckham, are as follows, the first 

 being the stone extensively quarried for building, and the second that burned for lime by Mr. 

 Clapp near Caroline station:* 



1. 2. 



Calcium carbonate 47.904 52.22 



Magnesium carbonate 35.227 36.04 



Calcium sulphate 6.74 



Insoluble matter, chiefly silica 13.85 2.82 



Aluminic and ferric oxides 1.49 1.39 



Water and alkalies, undetermined 1.529 



100.00 99.21 



In the southern part of Kasota the upper layer exposed of this limestone has been used for 

 lime-burning. Of its character here Prof. Winchell writes:! "George C. Clapp 's lime-kiln and 

 quarry are five miles below Mankato, on section 17, township of Kasota, within the main drift 

 bluffs of the Minnesota, but on the terrace formed by the Shakopee limestone, and about a mile 

 from the river. His quarry, located near his kiln, exposes a fine gray limestone, about two feet 

 thick, sometimes less or more, graduating into the Shakopee stone which underlies. It is very 

 firm, little porous, and contains Orthis, at least, and affords the finest and purest limestone hith- 

 erto seen in the Shakopee stone This fine, compact texture, and gray color, are not con- 

 tinuous in the same horizon, in other places the harsh magnesian grain and arenaceous quality 

 existing in the same beds. Running along the river for several miles, sometimes touching the 

 river, and sometimes exposed back of islands that show the same, this limestone forms a bluff of 

 solid beds. Although there is usually a heavy talus covering the foot of this bluff, yet at several 

 points the identity of this horizon with that at St. Peter, and hence with that at Shakopee, is fully 

 established by the exposure of the underlying sandstone. It is seen at a point about two miles 

 below Mr. Clapp's farm. This bluff shows a good stone, as at St. Peter and Kasota, but is not 

 much quarried. Perhaps it is more arenaceous in patches'. It is blotched with whiter spots and 

 with soft chert." 



At the Kasota quarries the section, below the 3 to 5 feet of alluvial limestone gravel which 

 forms the surface, is this Shakopee limestone, thin-bedded for its first 4 or 5 feet, the lower part 

 of this being used for flagging; then thick-bedded, in level layers^up to two and a half feet thick, 

 of pinkish buff color, supplying the best quarry-stone, 4 feet; next, less evenly stratified, in layers 

 only one foot or less in thickness, and light-colored, 3 feet; beneath which it lies hi irregularly 

 curved beds, is coarse-grained and contains little cavities, as at Shakopee, and is mottled, in the 

 usual manner of this formation, with yellowish and pink tints. This limestone extends here some 

 20 feet in depth, being underlain by the Jordan sandstone about 40 feet above the river. 



Opposite to the city of Saint Peter, about a mile south of the highway bridge, and a similar 

 distance northeast from these quarries at Kasota, Prof. Winchell describes "another exposure of 

 the limestone, in a bluff along the roadside. It seems here to be more shattered and irregular, 

 and like the Shakopee stone. Lime burned here cannot be distinguished from the Shakopee lime. 

 About eighteen feet are seen, the lower part being in good heavy beds. The upper surface is 

 water-worn, and in the openings the Cretaceous has been deposited." 



'Seventh annual report, p. 33; eighth report, p. 151. 

 tSecond annual report, p. 144. 



