BLUE EABTH COUNTY. 



Cretaceous beds.] 



433 



where fills cavities in the Shakopee limestone. This order of deposition, first, clay, and later, 

 sand and sandstone, is also found in these beds on the Maple river. 



In South Bend, at David P. Davis' quarry, the section on the north side of the railroad is, at 

 the top, fifteen to twenty feet of Shakopeo limestone, in layers only a few inches thick, because of 

 weathering, for its upper three to five feet, but below forming beds from one to three or four feet 

 in thickness; containing many crevices and hollows up to twenty feet in diameter and ten to 

 twenty feet deep, filled with a compact clay, mainly white or gray, but in a few places of a brick-red 

 and elsewhere bluish green color (Fig. 23). Next below, this limestone appears, deceptively, to 



FIG. 23. CRETACEOUS CLAY IN HOLLOWS OP THE SHAKOPEE LIMESTONE, SOUTH BEND. 



a. Shakopee limestone. 'b. Cretaceous clay. c. Drift. 



be underlain by a nearly levelly stratified bed of this clay, four to five feet thick, lying on the 

 Jordan sandstone, which forms the lowest one to two feet of the section. The horizontal bed of 

 clay here is probably of small extent, filling a space from which the upper part of the friable sand- 

 stone had been excavated by running water. South of the railroad track, this stratum of gray 

 and green clay, two feet thick, becoming gray sand below, also two feet thick, is seen along a 

 distance of fifteen rods, overlain by limestone debris, and underlain by the Jordan sandstone. 



Professor Winchell has described* an instructive section of the Shakopee limestone and its 

 associated deposits of this clay, as observed in a cut near the railroad bridge which crosses the 

 Blue Earth river about a mile above its mouth. "This cut is perhaps 70 feet above the river, the 





FIG. 24. SECTION NEAR THE RAILROAD BRIDGE, MANKATO. 



a. Shakopee limestone, cut by the grading of the railroad. &. Weathered surface of same. 



c. Cretaceous clay, greenish blue, bedded. d. Drift. 



bank of which is composed entirely of rock, the lower portion of which is the Jordan sandstone, 

 and the upper the Shakopee limestone, the latter comprising about 20 feet. In general this raij- 



Seoond annual report, p, 178, 



38 



