558 



SCIENCE. 



LN. S. Vol. V. No. 118. 



the Society, medical men and over 300 invited 

 guests from the other scientific societies of 

 Washington. V. K. Chesnut, 



Secretary. 



GEOLOGICAL SOCIETY OF WASHINGTON ; MEET- 

 ING OF MAECH 10, 1897. 

 The Geological Relations of some Southern Iron 



Ores. By C. Willard Hayes, U. S. G. S. 



Notwithstanding all that has been written 

 concerning the Southern iron ores, there has as 

 yet been no satisfactory statement of their 

 geological relations. This is particularly true 

 of the brown ores or limonites. The latter are 

 separated by the writer into two classes, the 

 gossan ores and the brown, valley ores. The 

 latter class is by far the most important. An 

 examination of many hundred deposits in con- 

 nection with the study of the areal geology of 

 the region in which they occur has led to a 

 classification in three groups depending on their 

 genesis and present relations. The first group 

 comprises a large number of deposits composed 

 chiefly of gravel ore imbedded in red clay near 

 the top of the Knox dolomite. During the 

 period of Tertiary baseleveling, the Chicka- 

 mauga limestone, which overlies the_^Knox dolo- 

 mite, was reduced to baselevel somewhat before 

 the latter, and areas underlain by the limestone 

 received the drainage from adjacent areas of the 

 dolomite. Deposits of bog ore were there 

 formed, and when the limestone was again re- 

 duced to a lower level, shortly after the eleva- 

 tion of the region, a part of the ore deposits 

 were left at the altitude of the Tertiary pene- 

 plain, forming a fringe about the depressions 

 which resulted from the removal of the lime- 

 stone. Deposits belonging to the second group 

 occur along the base of Cambrian quartzite 

 ridges where the quartzite passes with steep dip 

 beneath the siliceous limestone underlying the 

 adjacent valleys. The deposits are regarded as 

 segregations of the iron originally disseminated 

 through the limestone, concentrated upon the 

 impervious bed of quartzite during the progress- 

 ive reduction of the limestone surface. In the 

 third group are the extensive deposits associated 

 with the numerous thrust faults of the region. 

 While the deposits belonging to the two groups 

 above described are due wholly to the surface 



concentration of disseminated iron, the deposits 

 of this group are produced, in part at least, by 

 iron brought in solution from considerable 

 depths below the surface. Their character de- 

 pends largely on the kind of rocks cut by the 

 fault. Where these are quarizites the iron may 

 be in the form of ocher directly replacing the 

 silica, or it may occur as the cement in a fault 

 breccia or rarely, filling true fissure veius. The 

 largest deposits occur in connection with faults 

 between quartzite and limestone or between two 

 limestone formations, where they are intimately 

 associated with deposits of bauxite, the hydrated 

 oxide of aluminium, and the two ores are prob- 

 ably closely connected in origin. 



Geologic Notes on Kansas, Oklahoma and In- 

 dian Territory. By T. Wayland Vaughan, 

 U. S. G. S. 



Mr. Vaughan presented the results of a gen- 

 eral reconnoissance made from Muskogee, I. T. , 

 via Tulsa, I. T., Perry, Enid and Alva, Okla- 

 homa, to Coldwater and Medicine Lodge, Kan- 

 sas ; thence back to Coldwater, and south by 

 Woodward, old Camp Supply, Taloga, Arapaho, 

 to the Wichita mountains, in Oklahoma. The 

 journey from Muskogee to Medicine Lodge was 

 made in company with Professor L. F. Ward. 

 The Wichita mountains were reconnoitered as ftir 

 west the North Fork of Red River, east of 

 Mangum, and along their northern side east- 

 ward to Ft. Sill, at their eastern end ; thence 

 eastward, keeping on the north side of the 

 Arbuckle Hills. 



Mr. Vaughan considered the Tishomingo 

 granite (of Mr. Hill) in the Choctaw Nation, as 

 probably of Archtean age. The axis of the 

 Wichita mountains consists of solid plutonic 

 masses, forming numerous isolated peaks, or 

 groups of peaks, separated by wide, very level, 

 grass-covered valleys. The mountains are very 

 rugged and precipitous, and rise from several 

 hundred to more than a thousand feet above the 

 valleys between them. A series of the rocks 

 collected was found to consist of hornblende 

 granites, which form most of the mountains, 

 and an interesting series of gabbro rocks. The 

 rounded hills northwest of Ft. Sill are composed 

 of quartz poryhyry. The age of the plutonic 

 axis of the Wichita mountains is still undeter- 



