:;:;(, THE GEOLOGY OF MINNESOTA. 



I Shakopee limestone . 



in so many cases, except that in this instance the effect is somewhat in- 

 creased by the direct action of the Zumbro's waters. 



The. Slml-opev linn^fone. The area of this formation in the county is as 

 follows: It follows the larger streams, beginning on them when well in 

 the county, and broadening out until it leaves the county with them. It 

 appears in the beds of the branches of the Zumbro far up in Rochester, 

 Marion. Haverhill and Cascade townships. Rochester lies on a floor formed 

 by the upper surface of this formation. The valley of Rochester city is 

 entirely shut in by bluffs, except where the Zumbro passes out to the north 

 and along a geological valley, now dry, to the northwest. This valley of 

 Rochester- city is somewhat crab-shaped, and is formed by the meeting of 

 the various streams which make up this branch of the Zumbro. Cascade 

 township is about half occupied by the Shakopee, the remaining surface 

 being occupied by spurs and islands of the formations above, one of these 

 islands being quite large. Oronoco township is mainly underlain by this 

 limestone, closely associated along the river valleys with the Jordan sand- 

 stone and the St. Lawrence. Farmington has a Shakopee floor, except the 

 southern edge and some outliers of Trenton and St. Peter. In New Haven the 

 middle fork of the Zumbro soon rises to the Trenton, while the north fork- 

 lies on the Shakopee or Jordan, until it passes into the next county west. 

 A large portion of Quincy and a little of the northeast of Viola are on the 

 Cambrian. An arm of the same appears at the surface in the bed of the 

 river, passing nearly through Dover from east to west. Elmira is also 

 floored with the Cambrian for the most part, as is a small portion of Orion. 

 The village of Dover lies in a Cambrian valley, something like that of 

 Rochester city. The same is true of Chatfield. Something more than 20 

 per cent, of the county has a floor of these alternating sandstones and dol- 

 omites. 



Illustrative of the lithological characters of this limestone the following 

 section may be taken. It occurs at Quiucy: The same broken and con- 

 fused stratification accompanies the Shakopee throughout the county, and 

 may be seen in some quarries near Rochester.* 



Descending section at Quincy, Olmsted county. 



No. 1. Dolomitic limestone; quite arenaceous, falling out in huge masses which are rough, 

 distorted in their crude bedding, and unmanageable as a quarry stone, showing much calc-spar. 



*Sec also the description of the Shakopee in Eice and Dakota counties. 



