474 T. C. Brown — Shawangunh Conglomerate. 



and grading into, the Rosendale cement bed of the Upper 

 Silurian. 



The red color of the High Falls shale, which has been con- 

 sidered an evidence of the deposition of these beds under 

 desert or at least subae'rial conditions, is not an original char- 

 acter, but has been produced by comparatively recent weather- 

 ing and practically fails where these beds are uncovered away 

 from the outcrop or the effects of circulating ground waters. 



The pure white color of the Shawangunk conglomerate with 

 included layers of bright green shale cannot be readily ex- 

 plained on the theory of subae'rial deposition, under the arid 

 climatic conditions postulated for Salina time, and the fine- s 

 grained sandy character of this formation throughout the 

 greater part of its depth is hardly consistent with the torrential 

 theory of its origin. 



The presence of considerable quantities of iron pyrite in the 

 High Falls shale and upper part of the conglomerate is not 

 consistent with the subae'rial, alluvial fan theory of origin in an 

 arid Salina climate. The green color of the shale layers in the 

 conglomerate and their great preponderance in the un weathered 

 sections of the High Falls shale as well as the presence of iron 

 pyrite in the latter formation indicate that the beds were 

 deposited under conditions such that the iron was subjected to 

 reduction, not oxidation. This would imply either subaqueous 

 deposition or the presence of abundant vegetable or other 

 organic matter. We have no evidence that land vegetation 

 was abundant during the Salina epoch and the total lack of 

 fossils would further indicate that the reduction was not 

 brought about by organic matter. It seems necessary, there- 

 fore, to conclude that these formations were deposited under 

 water. 



The thin-bedded Binnewater sandstone containing consider- 

 able amounts of calcium carbonate and grading upward into 

 the hydraulic cement bed and then into the normal marine 

 Cobleskill limestone cannot be explained, in so far as the 

 writer can see, as other than a normal marine shaly sandstone. 

 In this region, at least, there is no trace of a great break or 

 hiatus during, or at the close of, this formation. 



These facts lead to the unavoidable conclusion that in this 

 region these three formations constitute a normal sequence at 

 the base of a normal marine transgression during Salina and 

 Upper Silurian time. They are overlapped to the north and 

 east by higher beds, as we should expect in such a normal 

 transgression. These beds cannot be interpreted as subaerial 

 deposits of the alluvial fan type, and there is no apparent 

 reason why they should be considered delta rather than normal 

 shore deposits. 



Bryn Mawr, Penn. 



