EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 63 . 



The brilliant red colors of the Bonaventure conglomerate and the sand- 

 stones which lie over the broken limestone folds of the region and give 

 color to the soil, do not at this point concern us. Their significance as 

 evidence of deposition of the sands in shallow waters is confirmed by all 

 collateral evidence from stratigraphy, geography and fossils. But it is of 

 immediate importance to know if such colors in the limestones point to 

 similar conditions. We may therefore make reference to recent publica- 

 tions upon this theme b)' Spring' and Moberg." 



The former of these writers has considered the subject from the purely 

 chemical and empirical standpoint. The latter has treated it on the basis 

 of paleontologic and bathymetric evidence. The conclusions of both are in 

 essential harmony. 



The red oxids coloring limestone strata are evidence of deposition of 

 the sediments in waters sufificiently shallow and near enough to the coast 

 to be subject to the effects of the organic acids brought down to them l)y 

 terrestrial drainasfe. The effect is facilitated and in notable measure condi- 

 tioned by ready oxidation, involving the conception of occasional exposure 

 as calcareous mud fiats to the direct action of the atmosphere. Katzer,^ 

 who has also closely studied these phenomena, suggests exposure to 

 sunlight as an active agency in the effect produced. 



These conclusions, arrived at from such different points of view, are of 

 profound concern and compel us to revise the commonly accepted notion of 

 the bathymetric conditions of limestone deposition. When prevented from 

 exposure to air and light or far enough distant from the coast to be out of 

 reach of terrestrial acids, the color oxids do not form. Thus a highly 

 colored limestone may be stratigraphically continuous with one of neutral 



'Spring, W. Ueber die eisenhaltigen Farbstoffe sedimentiirer Erdboden und uelier 

 den wahrscheinlichen Ursprung der rothen Felsen : Neues Jahrb. fiir Mineral. 1899. 

 1:47. 



^Moberg, J. C. Om rodfargade lager inom Sveriges Kambro-silur: Geol. Foren. 

 i Stockholm Forh. 1904. 26 : 134. 



3Ueber die rothe Farbe von Schichten-gesteinen. Neues Jahrb. fiir Mineral. 1899. 

 I :i77. 



