14'J TIIK 1M;N<)KKK IllONllKAKMNC SKIMMR. 



Clicrt iiccurs in llic iloldiniU' iVoiii minute |(;irticl('s tliroiiuli tliiii hiyeivs, 

 nli'nli |)riiliii(lc 111! tlic wcalluTcd surt'ave in loaf-like t'orms, ii|» to belts 

 whicli are If) or W I'eel tliii'k. 



'riie cliaiiiic iVoni llie (/luTly limestone to the ovi^'lyiufi' Quartz-slato 

 inemher is iisiiail\ alinipt, wliile in luaiw places lietweeii tlie two lliero 

 is eertaiii e\ ideiiee ot an erosion inter\al. 



The chert and limestone are water-deposited seilinients. Whether 

 chemieal or organic is untH-rtain, Itnt it is not improhalile that tlu'V are partly 

 or whollv the latter. Il«>\V(>\'er, it' this is the ease, the silica has suhso- 

 (|n('ntl\- chaiif^-ed to tiie mineral I'orm and has Ixh'U oxteiisivoly rearranged, 

 w hile llie linu^stoiio has become dolomitized. 



