Sources of the Constituents of Minnesota Soils. 3(->7 



are washed to build a single meadow ; and these washed hillsides 

 are pre-eminently the barren pastures of grazing districts. 



The granitic rocks. — Granitic rocks are distributed very 

 largely over the northern part of the state. Probably one-half 

 of the area north of the line from Taylor's Falls to Anoka 

 and thence directly westward to the state of South Dakota 

 through New Ulm and Tracy is underlain, beneath the glacial 

 drift, by these rocks. At many places when the granites come to 

 the surface samples have been taken for study. Below are a few 

 analyses made of granites and gneisses from representative locali- 

 ties : 



I. Red hornblende biotite granite, St. Cloud, analysis by 

 F. H. Crowell. 



II. Gray hornblende biotite granite, St. Cloud, analysis by 

 W. H. Willard. ' * ' 



III. Gray augite granitoid gneiss. La Framboises farm be- 

 low old Fort Ridgely ; analysis by A. O. Dinsmore. 



IV. Medium colored hornblende biotite granite, St. Cloud ; 

 inalysis by G. H. Hammond. 



V. Red hornblende biotite granitoid gneiss, Ortonville ; an- 

 alysis by A. D. Meeds. 



(This is the stone of which the City Hall and Court House in 

 Minneapolis is built.) 



VI. Augite gneiss. La Framboise's landing below Ft. 

 Ridgely, Otto H. Folin. 



II 



III ! IV I 



VI I Average 



Silica SiOz 



Alumina ALOs . . 

 Ferric oxide Fe20o 



Lime CaO 



Magnesia MgO . . 



Potash K2O 



Soda NaaO 



V^ater H2O 



Totals 



73.30 

 14.20 

 5.40 

 300 

 0.50 

 1.40 

 2.00 

 0.30 

 100.10 



71.64 

 11.82 

 3.94 

 1. 41 

 0.32 

 2.49 

 5.22 

 0.88 

 97.72 



72.30 



15.40 



3.10 



3.75 

 0.65 



3.40 



2.00 



100.50 



69.47 

 14.94 

 4.07 

 1.60 

 0.29 

 4.56 

 Z-Z7 



98.30 



74.70 



14.06 



*5.07 



1.73 



0.29 



1.83 



2.17 



0.26 



100. II 



69.07 



13.73 



*2.87 



3-70 



7.08 



4.30 

 0.13 



71.71 ^ 



I4.02J4 

 4-07^2 

 2.53 

 •52 



2.10 

 3.39 

 .59^1 



97.05 98.98 



^FczOa and FeO computed together. 



The foregoing analyses were made from fresh material, in 

 some instances broken from the lowest layers in the quarry. 

 They thus represent not partially decomposed rock formations, 

 but the actual condition of the freshest and least changed beds 

 within the granitic group of Minnesota rocks. The soils orig- 

 inating directly from them are as varied in composition as are the 

 rocks themselves ; so they vary from a sandy soil on the one hand 



