BUFFALO SOCIETY OF NATURAL SCIENCES l8l 



fossils are all mollusca and brachiopods, are numerous and well- 

 preserved, a fact not compatible with the reasoning of Macnair and 

 Reid. As has been fully explained by Grabau, the main mass of the 

 Bays represents an alluvial fan spread out on the land and having its 

 western and southernmost margins extending into the sea. Thus it 

 was possible for some of the highly oxidized sands to be carried out 

 to sea, where they were deposited and where marine fossils were 

 entombed with them. There is, therefore, nothing inherent in poten- 

 tial red deposits to prevent marine shells from being preserved in 

 them; the difficulty lies in the fact that great thicknesses of potential 

 red beds can not be deposited under conditions where it is possible 

 for marine animals to leave their record, because such deposits must 

 be formed on the land. As for the inimical effects of iron peroxide, 

 it need only be stated that the reddest of deposits contain only a 

 small amount of iron 14 and that it is not the amount but the fineness 

 and perfection of dissemination of the iron that are responsible for 

 the color (Grabau, 87, 621). That sandstones made up of grains of 

 pure silica are bad media for the preservation of molluscs is easily 

 disproven, for one need only recall such highly fossiliferous formations 

 as the Oriskany sandstone and the Schoharie grit of the Devonic 

 of New York, or the Miocenic sands and conglomerates of the Vienna 

 Basin. The reason why so many sandstones are unfossiliferous is 

 generally that they were deposited as terrestrial sediments either 

 fluviatile or eolian. 



(b) Marine denudation. A second argument advanced by Mac- 

 nair and Reid is based upon the assumption that the erosion of the 

 Siluric rocks in the Highlands of Scotland was due to marine denuda- 

 tion and upon faulty observations at certain localities. They argue 

 ''The marine denudation of the Silurian rocks of the Highlands of 

 Scotland is not in dispute, but Ramsay and Geikie have assumed a 

 subsequenc lake or fresh-water denudation." The conformable depo- 

 sition, however "of the Old Red Sandstone upon the preceding Upper 

 Silurian deposits in the counties of Edinburgh and Lanark, the Welsh 

 area, and in the St. Lawrence basin, precludes any such idea; for from 

 the base of the Upper Silurian to the top of the Lower Old Red sand- 

 stone the sequence of these deposits is unbroken. It therefore follows 

 that the denudation of the rocks of the Highland area being marine, 

 the equivalent deposits occurring in the Upper Silurian and Lower 



14 The bright red Vernon shale (Salinan) has shown on analysis only 2.25 per cent of ferric oxide 

 and 0.75 per cent of ferrous oxide. 



