THE ORIGIN OF RED BEDS 



161 



The following analyses are taken from W. J. Miller: 1 



Vernon Formation, Central New York 



*The greenish sandstone of the Chugwater in this case is a strip of the ordinary red sandstone, 

 leached along a joint crack. 



The following analyses are taken from Richardson: 3 

 Spearfish Formation, Black Hills 



The black color in the slates is due, not directly to any peculi- 

 arity of the iron content, but to the presence of carbonaceous 

 matter, which incidentally brings about the reduction of iron oxide 

 to the ferrous form. Black shales are very rare in the western Red 

 Beds, but highly carbonaceous and even coal-bearing strata occur 

 in the Newark series of the Atlantic Piedmont. The typical 

 Newark elastics are quite intensely red, many of them with a 

 purplish tone, but the carbonaceous strata are always gray or black. 



The color of the prevailing red strata in the Red Beds series is 

 due to the presence of ferric oxide. The iron of the coloring matter 



1 W. J. Miller, "Origin of Color in the Vernon Shale," Bull. N.Y. State Museum, 

 No. 140, in 63d Ami. Rept. N.Y. State Museum, igog, I, 150-56. 



2 U.S. Geol. Survey, Division of Chemistry, Analysis No. 2530. 



3 G. B. Richardson, "The Upper Red Beds of the Black Hills," Jour. Geol., XI 

 ( I 9°3), 365-93- 



