BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 5, pp. 357-366, PLS. 15, 16 MARCH 24, 1894. 



PRE-PALEOZOIC DECAY OF CRYSTALLINE ROCKS NORTH 



OF LAKE HURON 



BY ROBERT BELL 

 ASSISTANT J)rRECTOH OF THE GEOLO(iICAL SURVEY OF CANADA 



(Bead before the Society December 28^ 189S') 

 CONTENTS 



• • Page 



Relation oT Archeaii to Paleozoic Rocks ?,Tu 



Evidence of pre-Paleozoic Decay ;]5<S 



AVhere best displayed o5<S 



" Ovens " or Pits of Decay 3o8 



Rocks of the Huronian Belt ool) 



Ancient Erosion 3">1> 



Typical Erosion Snrface ^).')0 



Conditions affecting Erosion .'{(il 



Contacts of Archean with Paleozoic Rocks ^ ?)()2 



River and Lake Channels dne to Rock Decay 'M'A 



Absence of Paleozoic Deposition and its SiirniHcance ;>()() 



Effect of iilacial Denudation :>()() 



Rel.vtiox of Arctiean to Vm.vay/amv, Rock.'^. 



In all parts of Canada where the Paleozoic strata come in contact with 

 the nnderlying Archean rocks the latter appear to ])ass beneath them 

 with' very much the same contour or slo})e as that of their modern sur- 

 face. It appears evident that these ancient stratified or laminated rocks 

 liave ])een tilted to their present high angles, and that-their included in- 

 trusive masses, whether of granite or greenstone, and even most of their 

 dikes, have occupied their present positions relatively to each other before 

 the commencement of Paleozoic time, excepting in cases where faulting 

 has taken place. Not only is this so, but at that early date they appear 

 to have been worn down by denudation .to something like their present 

 superficial aspect. 



What has become of the vast amount of debris resulting from this 

 denudation ? This is a in-oblem of American geology which has not 



L-BuLi-. Geol. Soc. Am., Vol. 5, 1893. (^^'>") 



