456 A. W. GRABAU PALEOZOIC DELTA DEPOSITS <~>F NORTH AMERICA 



rock, with the inclination of the beds all directed the same way. which is 

 toward the north. The rock seems to be especially coarse on the diagonal 

 layers, the horizontal ones between them being somewhat finer. The 

 thickest of the diagonal bedded layers measured 1? inches, which is not 

 much above the average, though some of these beds are only 1 or 2 inches 

 thick. Three ledges of this character appear in a space of 1 1*» feet, dip- 

 ping at an angle of nearly 45 c southeast, though in one c-ase this chang - 

 to 30° southeast. They are separated by : . intervals, probably 



underlain by shales. These sandstones have been referred to the Sevier, 

 which is here about 1,300 feet thick. They apparently represent the ex- 

 treme outer portion of a white quartzose fan of subaerial origin, similar 

 in character and development, though probably not in extent, to the Bald 

 Eagle delta fan of the region farther north. 



Above these sandstones the outcrops are concealed until we come to 

 within about 100 feet of the bottom of the Clinch sandstone, which forms 

 the crest of the mountain. The lowest beds shown are heavy bedded red 

 sandstones, with strong cross-bedding of the torrential type. Then fol- 

 lows a red shale, strikingly resembling the Queenston shale of the Niagara 

 ge 5 and above this are more sandy beds partly red and partly mottled. 

 containing small pebbles and vertical tubes filled with fine mud and 

 probably referable to Scolithus veriicalis of the Medina. Some of these 

 beds are cross-bedded, as is the case in the lower sandy layers, the dip of 

 this cross-bedding originally pointing northward. Among the float on 

 this surface I found a specimen of Arihrophycus harlani in a piece of 

 reddish sandstone apparently of this horizon, thouglr it may have come 

 from the Clinch, which has several iron-stained layers. Whether this is 

 the case or not. it. nevertheless, seems quite likely that the upper diag- 

 onal bedded sands with Scolithus tubes are of Medina age. representing 

 the reworked sands derived from the erosion of the southeastward exten- 

 sion of the Bays sandstone, when this was brought into the erosion zone 

 by the Taconic elevation. This would put a pronounced hiatus between 

 the red shales and the sandstones, the former being late Ordovicic. the 

 latter early Siluric. 



Whether these red beds come to an end farther to the northea- 

 whether they are continuous with the Juniata of western Maryland, has, 

 I believe, not been asrertained. In Highland County. Virginia, and in 

 the counties immediately to the south and east ( Staunton quadrangle 1 ! 

 they seem to be represented by the lower part of the Massanutten sand- 

 stone. This formation. 500 feet or less in thickness, comprises an upper 

 whit _ v qnartzite. which represents the Clinch of the south or the 



