152 NEW YORK STATE MUSEUM 



oxid is thus very small, but, because of its fine state of division and 

 its diffusion through the mass, it has become very effective as a 

 coloring agent. BarrelP discusses this point and believes that where 

 even a very small percentage of the ferric oxid is thoroughly dif- 

 fused through a rock mass it has great coloring power. It should 

 be stated that after treatment with the hot acid a green insoluble 

 residue is left, whose color disappears after prolonged boiling with 

 concentrated sulfuric acid. Under the microscope this green 

 residue, whose coIot is doubtless due to the presence of glauconitic 

 material, looks like the ordinary red shale except for color. The 

 final residue is made up chiefly of clear, tiny quartz grains. The 

 relation of the ferric oxid to the glauconite could not certainly be 

 made out but they appear to be very intimately mixed in the earthy 

 matrix surrounding the quartz grains. The origin and significance 

 of the glauconite will be taken up later. 



We may now inquire whether ot not the red color was present 

 when the shale was deposited.. According to Russell's^ hypothesis, 

 namely " that the sands forming the sandstones of the Newark 

 system and other similar formations received their incrustation of 

 ferric oxid (red) during the subaerial decay of the rock from 

 which they were derived," the red color was present at the time of 

 deposition. BarrelP comes to quite the opposite conclusion, espe- 

 cially with reference to red beds associated with salt and gypsum 

 las e. g. in Nova Scotia, the Permian red beds east of the Rockies, 

 etc. Like these red beds, the Vernon shale is also associated with 

 salt and gypsum and was also deposited in rather highly saline 

 water under an arid climate. As Barrell^ says the lack of the red 

 color at the time of deposition is well borne out by the " usual 

 present development of salt and gypsum in association with gray 

 or yellow sediments." He cites such examples as the Dead sea and 

 the salty flats of the Great Basin of the United States. It is evi- 

 dent that red or reddish brown colors greatly predominate in ancient 

 iron-bearing formations, while the yellow tones, outside of the 

 tropics, are much more characteristic of the modern alluvium. 



It is well known, especially as a result of the Qiallenger^ dredg- 



^ op. cit. p. 289. 



^ op. cit. p. 56. 



' op. cit. p. 290. 



" op. cit. p. 290--91. 



5 Challenger Report on Deep Sea Deposits, p. 337 et seq. 



