Sources of the Consfifuents of Minnesota Soils. 



399 



XI. Peridotite, Minnesota river bottoms below Motley; 

 analysis by A. D. Meeds. Bull. 157, U. S. Geol. Survey, Granites, 

 granite gneisses, etc., of the Minnesota river valley, p. 113. 



XII. Porphyritic gabbro schist, Granite Falls; analysis by 

 E. J. Babcock. Bull. 157, U. S. Geol. Survey, p. 89. 



XIII. Porphyritic diabase near the base of Caribou Peak, 

 north shore Lake Superior; Professor C. F. Sidener. 



XIV. OHvine gabbro, Sec. 19, T. 65, R. 9 W. ; Dr. H. W. 

 Stokes. Journal of Geology I, p. 712.'^' 



XV. Normal gabbro, Sec. 35, T. 61, R. 12 W. ; Dr. H. W. 

 Stokes. Journal of Geology I, p. 712.''' 



♦CO2 = 1.12 %. tincl. NiO 0.16 and P2O5 0.05. JIncl. NiO 0.04 and P2O5 0.02. 



Sandstones and qiiartsites. — The third group embraces typi- 

 cal sandstones and quartzites. These rocks do not lie in distinct 

 and broad areas; they are rather in the form of narrow belts 

 sandwiched in between the dolomitic rocks in the southeastern 

 counties and the eruptive flows of northeastern Minnesota, save in 

 the one expanse of quartzite which appears around N"ew Ulm, 

 thence southwest and across Cottonwood, Rock and Pipestone 

 counties into South Dakota and Iowa. Attention is called to the 

 high percentage of silica in these rocks. 



XVI. Red quartzite, Pipestone; analysis by Professor J. A. 

 Dodge. 



XVII. Pink sandstone, Hinckley; analysis by Professor J. 

 A. Dodge. 



XVIII. White Saint Peter sandstone, Fort Snelling; anal- 

 ysis by Professor J. A. Dodge. 



* Nos. XIV and XV were inserted in the reprinting of the Bulletin because 

 of their typical character. 



