EELATION OF CEETAlN ROCKS 429 



stones and shales were also firmly cemented through the precipitation of 

 material from these hot solutions, the cementation being accompanied by 

 the development of chlorite. Nothing is known as to the depth from 

 which the hot water came or its method of origin. 



Kelation of the altered Eocks to the Lead and Zinc Deposfts of 

 southeastern kansas^ the eose boulders, and the grranites 



REPORTED FROAC THE DFEP AYeLLS OF CiFNTRAL KANSAS 



The recognition of the fact that Pennsylvanian strata of eastern Kan- 

 sas have been altered by hydrotliernial processes raises three questions. 

 They are as follows: (a) Is there any relation between the metainorpliism 

 which has occurred at Silver City and the lead and zinc ores wliich are 

 found in the near vicinity?^ (h) Does tlie fact of alteration liave any 

 bearing on the origin of the granite porphyry boulders which occur in the 

 vicinity of Eose, only about 6 miles to the north ?^ (c) Is there any 

 connection between the granite reported in deep wells of central Kansas 

 and the metamorphism at Silver City? These three questions will be 

 considered in detail. 



(a) No lead or zinc minerals have ever been noted in the altered rocks 

 of Silver City, so that it is quite unlikely that the formation of the 

 quartzites and related rocks are related to the development of the lead 

 and zinc deposits. 



(h) While studying the boulders at Eose, the writer tested as one 

 hypothesis of origin the possibility that they might have been derived 

 from a dike, sheet, or flow. It was pointed out that a small fjiuirtz vein 

 had been observed a distance of a quarter of a mile from the Iwulders, 

 and it was stated that the alignment of the greater portion of the material 

 is in harmony with the idea that the boulders are parts of an extrusion 

 or intrusion; but the coarse-grained character of the material, the absence 

 of metamorphism and contiguous deformation caused the hypothesis to 

 be rejected. Since that paper was written the writer's attention has been 

 called to the fact that three wells have been drilled on the southeastern 

 margin of the area over which the })Oulders are distributed, each reaching 

 the Mississippian limestone. No alteration of strata is reported to have 

 been found in the wells, nor was any igneous rock enconntered. One of 

 the wells is said to have produced gas for several years. The evidence of 

 the wells supports the view that thei-e is no intrnsion or extrusion present 



Haworth : Kansas Univ. Oool. Surv.. vol. viii, 1904, p. 43. 

 Twenhofel : Am. .Tour. Sci., 1017, p. .363. 



