PALEOZOIC ROCKS OF THE CANTON QUADRANGLE I9 



at the meeting of Grenville quartzite and marble, and consist mostly 

 of a reconsolidated ferruginous earth, with some silicious frag- 

 ments, or else of a silicious regolithic breccia whose cracks and 

 interstices often gleam with "combs" of crystalline quartz and 

 hematite. Some of the most beautiful of these mineralizations 

 come from the tiny outlier at Mr Dillabaugh's (locality 85) in the 

 southeast corner of the quadrangle. 



Where there has been some reworking of the talus adjacent to 

 a cliff, we have brilliant " calico conglomerates," with a deep-red 

 or blood-red sand-matrix inclosing all-sized rounded to angular 

 fragments of white, yellowish and reddish quartzite, or dull-red 

 jasper. In some cases the sand-matrix becomes jasperized and 

 the rock closely approaches certain portions of the Grenville in 

 appearance, possibly because the jasperization of both rocks was 

 accomplished simultaneously. This may have been by hot alkaline 

 waters working up from beneath through the limestone, but whether 

 these were the same mineralizing solutions that put the zinc in the 

 latter at Edwards and converted its tremolite into talc, or whether 

 they were of later date, can not now be said. In any case they 

 have not lightened the task of mapping the frayed and tattered 

 contact line in which no real division plane exists. A visit to 

 localities 74 and 75 will show how hopeless is the attempt to por- 

 tray the facts on a map, even where the rocks are completely bare. 



But there are other localities, for example yj, where the contact 

 of the two rocks is abrupt, suggesting an ancient sea-cliff slowly 

 drowned and silted over by advancing waves. It is noteworthy 

 that such occurrences are chiefly in the upper white beds of the 

 Potsdam series, a division that bears more evidence of construc- 

 tion in and under water than do the lower, possibly anemoclastic 

 and continental, red beds. Yet even here the Potsdam is always 

 so thoroughly bonded to the rock beneath that only closest scrutiny 

 reveals the division line; and nowhere has the writer seen the two 

 rocks tending to separate smoothly from each other on weather- 

 ing, as do all the higher formations. The one has arisen largely 

 from the dissolution of the other in situ. 



interpretations so far as they are applicable to our deposits. It may be 

 safely asserted (a) that the ore was residual from the crystallines, likely 

 including the oxidation of pyrite as Smyth surmised, (&) that it was 

 washed down into the miarble valleys and there precipitated, probably by 

 reaction with the limestone, and (c) that to the associated quartzite bands 

 we owe in our region the preservation of the existing patches from 

 erosion long subsequent. 



