PHYSICAL CHARACTERS OP SHAKOPKK r)()L()^^ITIC. 181 



some of the layers tliat obtain there is a predc^minance of (juartz sand, 

 while others are fine shaly layers, often broken into isolated ])ockets. 

 The base of the Shakopee has generally an oolitic layer — as, forexam])le, 

 at Mankato, Minnesota — sometimes mixed with quartz sand, as at New 

 Richmond, Wisconsin ; the main body of the formation here and there 

 contains pockets of sand, oolite, or clay, wliile tlie ii[)i)er strata are 

 largely composed of sand, l>et\veen which are dolomites, with Shakopee 

 fossils, wherever fossils occur. This lithologic condition gives the ap- 

 pearance of stratigraphic unity l)etween the Shakoi)ee and the overlying 

 Saint Peter, which McGee has noticed in Iowa. '^ In Wisconsin, on the 

 other hand, shales in places re})lace the sandy layers of the top of the 

 Shakopee and the lithologic delimitation becomes as sharj) as the paleon- 

 tologic. 



The folding in the top of the Oneota is carried upward into the Shak- 

 opee and even becomes increased in this formation, as can be clearly 

 seen in some localities, while elsewhere the yielding layers of the New 

 Richmond sandstone seem to afford a line of readjustment. Elxtreme 

 folds usually abound in cryptozoonic concretions. Sometimes even these 

 concretions are tound broken, forming a breccia or pseudoconglomerate 

 with a sandstone, but more usually dolomite, matrix embedded in the 

 mass of the Shakopee. 



When fossils are found in the Shakopee they are very numerous. 

 They are also very fragmentary, owing to the universal dislocation which 

 the strata of this formation have undergone. 



FA UXA L CIIA RA CTERS. 



The f^una of the Shakopee is very well defined. Its forms assure the 

 writers in the statement made in the taV)le on page 170, locating the series. 

 Present identifications place them in the genera Murchisnnid, RdpJiistoma, 

 and Sidmlites, which are very similar to species described by J^illings 

 from the upper Calciferous. A few specimens of Eadoceras and Lilnites 

 also occur. 



The best localities for gathering the above are Shakopee, Cannon Falls, 

 and several places in Winona county, ^linnesota, and at Argyle and 

 near Hudson, in Wisconsin. 



ThK LTTFIOLOr;Y OF THE SeUIES. 



riiE SAyDsroNEs. 



Tlie litliologic characters of the Upper Caml)rian sandstones may be 

 succinctly stated. Their chemistry promises so few results new to geolo- 



* Pleistocene History of Northeautern Iowa, p. 331, already cited. 



