iyZ Notes </n the Local Geologij of MiDilaito ~ BerhdoJt. 



x\» fast as this was removed because the overlyiiiij: strata liave not 

 been disturbed. 



Character of the clays: — I have not been able, after repeated 

 search, to detect tlie slightest trace of an}' fossil, animal or vegeta- 

 ble, large or minute, in these clays. Regarding them as cretaceous, 

 this was a surprise to me, even the miscroscope would reveal no 

 fragment of vegetable or animal organism. 



These clays are not uniform in color, while the prevailing 

 tint is white, bands of a pink, and a drab color are found; there is 

 no uniformity of arrangement. 



They are not uniform in composition, while most of the clays 

 do not effervesce with chloric hydrate, ( a surprise to me and in 

 this respect not agreeing with a sample of cretaceous clay from 

 Dakota) other layers may effervesce. Calcic carbonate as well as 

 ferric oxide are therefore to be regarded as accidental impurities. 

 Some of the layers are very free from grit, smooth and soapy to 

 the touch, others are gritty and this grit varies from an impal- 

 pable powder, only distinguishable under the teeth or with a 

 microscope, to rounded grains of white siliceous sand. As a rule 

 the clay along the sides is finest and the most grit is in the centre 

 of the fissure and in the lower layers. In some of the larger 

 fissures, throughout the length of the fissure and in the direction 

 of the former flow of the trickling water are found angular frag- 

 ments of white sandstone, resembling the Jordan sandstone as 

 seen here or the St. Peter as exposed in the bluffs at St. Paul. 

 These angular fragments of white sandstone are also found in 

 crevices in the Shakopee above Mr. Beatty's quarry, northeast of 

 the city. 



These are the facts that make it seem more than likely to me, 

 that these clay deposits were formed from material taken up by 

 water precolating through the St. Peter sandstone, while it was 

 yet in position over the Shakopee, carrying away the clay, fine 

 sand, etc., in suspension to deposit it in the lower and slower part 

 of the underground course, just as a stream does. I have had no 

 opportunity to examine the St. Peter sandstone, but presume that 

 like the Jordan it contains throughout its mass lumps of clay, the 

 source of these deposits. The origin and character of the rock makes 

 this almost necessary. During the Drift period the St. Peter and 

 at places nearly all of the Shakopee were ground up, dissolved, and 

 swept away. They left behind broken fragments, sand, iron rust 



