72 AMADEUS W. GRABAU 



Niagaran fauna. This fixes the age of the Queenston and Juniata 

 as Richmond, so far as their major portion is concerned; though, as 

 already noted, the lower part must be considered as Lorraine (see 

 Fig. lo). 



In eastern Tennessee a second deposit of red sands of this period 

 forms the Bays sandstone. This is from i,ioo to 1,300 feet thick 

 in its maximum development near Loudon, but thins away by over- 

 lap in all directions. In some localities, as at Walker Mountain, 

 it is fossiliferous, carrying the late Lorraine fauna with Byssonychia 

 radiata, Modiolopsis modiolaris, etc. Wherever the contact with 

 the underlying Sevier shale is exposed, it is seen to be a gradational 

 one, the fossils extending part way up into the red beds. The basal 

 white bed, comparable to the Bald Eagle conglomerate, if it ever 

 existed here, was overlapped by the Bays, the portion east of the 

 overlapping edge having been removed by erosion. The Bays 

 may be regarded as an independent fan, or group of fans, of red 

 sedimentation with a distinct center of supply. 



The correlation of this series of continental sediments with the 

 contraction of the sea known to have occurred in Upper Ordovicic 

 time has not yet been attempted. It is not improbable that the 

 initial uplift of the land which caused the retreat of the sea, also 

 initiated the strong river-activities which resulted in the formation 

 of the Bald Eagle conglomerate and sandstone. This probably 

 corresponded to the period of folding of the Ordovicic and earlier 

 strata in New England and northward. If that is the case, the emer- 

 gence was probably post-Trenton, falling in early Lorraine (Frankfort 

 or Eden) time and extending toward the end of Lorraine time. The 

 period of red sedimentation in the east may have coincided with 

 the period of erosion in the upper Mississippi and Rocky Mountain 

 areas, and deposition of the Richmond in the narrow interior basins. 

 The late Richmond expansion may coincide with the climatic change 

 indicated by renewed river deposits of white C[uartzose material. 



D. THE LOWER SILURIC OR NIAGARAN 



The following divisions of the New York Niagaran are in common 

 use as the North American standard: Guelph, Lockport, Rochester, 

 Clinton. 



