GEOLOGY OF STEEP ROCK LAKE 723 



unconformable relation to a granite gneiss of the basement complex. The 

 conclusion is that the Steep Rock series was iinconformably deposited upon 

 the Keewatin. The probable imsition of the Steep Rock series in the geo- 

 logical scale is given as beneath the Aniniikie, with a series of quartzites and 

 slates, which is called the Seine series, between the Animikie and the Steep 

 Rock series. The discovery was announced that the limestone which was 

 estimated by Smyth to be not less than 500 or more than 700 feet in thickness 

 is fossiliferous. 



FOSSILS OF LOWER LTMFSTOXE OF STEEP IfOCK SERIES 

 BY CHARLES D. WALCOTT 



(Al)S tract) 



Notes on a description of a new genus and two species of sponges found by 

 Dr. Andrew C. Lawson in the limestone of the Steep Rock series. 



Discussion 



Prof. A. P. Coleman : It is extremely interesting to hear of the discovery 

 of distinct fossils in the Steep Rock series, which other geologists as well as 

 myself have believed to be Huronian. The limestones are very fresh looking, 

 but hitherto no well-defined fossils have been found in them. There are, 

 however, carbonaceous beds in the Huronian which have been thought to 

 imply life, even though fossils were not known. 



ORIGIN OF THE SEDIMENTS AND COLORING MATTER OF THE EASTERN 



OKLAHOMA RED BEDS 



BY J. W. BEEDE 



(Abstract) 



Recent investigations seem to show that the sediments of the lower red beds 

 of Oklahoma were derived from the Arbuckle- Wichita l*ermian land-mass. 

 The conclusion is based on the amount of material removed and the geo- 

 graphic distribution of sediments bordering the mountains. 



Coarse limestone conglomerates of great thickness and conglomerates of 

 crystalline rocks, both possibly of subaerial origin, dovetail into red beds. 

 Belts of sandstone have been found extending into the area of finer sedi- 

 ments farther away from the mountains, apparently indicating the location 

 of stream debouchures at the margin of the shoal sea. The extreme shallow- 

 ness of the water is clearly indicated in the structure of the beds. 



The coloring matter is thought to have been derived from the solution of 

 the 7,000 or 10,000 feet of pre-Carboniferous limestone which formerly cov- 

 ered the Arbuckle-Wichita Mountains and much of the surrounding region. 

 The solution of the limestone furnished optimum conditions for the oxidation 

 of its iron content, as it does at the present time in the limestone regions of 

 the Mississippi Valley, southern Europe, West Indies, and elsewhere. More- 

 over, the solution of the pre-Carl)oniferous limestones and the conglomerates 

 of the Arbuckle-Wichita region now in progress produces a red residuum 



