486 A. W. GRABAU rALEOZOIC DELTA DEPOSITS OF NORTH AMERICA 



Soft gray to yellow shale, overlying the sandstone. Feet 



Hard white to gray sandstone, thick bedded above. . thin bedded to 



shaly below 14 



Hard black fissile shale 1 



Hard sandstone with rough surfaces, stained yellow and red 10 



Hard black shale, sandy at top and pitted by rust-stained worm tubes ; 

 contains abundant fragments of a curypterid close to Hughmilleria 



social is M 6 



Irregular bedded sandstone 7 



Drab to pink shale with thin sandy beds at top. 



(Clinton) 38 



The occurrence of these Euiypterids, apparently identical with those of 

 the Shawangunk grit, is strong evidence for the Shawangunk-Pittsford 

 age of the sandstone, and it may be regarded as the attenuated outer edge 

 of the overlapping series of Shawangunk strata. Eastward in the quad- 

 rangle the Keefer sandstone increases to 50 feet, while westward it dies 

 out altogether, occurring only as a thin ripple-marked layer above the 

 eroded Xiagaran surface near Cumberland. 



The McKenzie formation. — The Keefer sandstone is succeeded by a 

 series of thin limestones and shales which have been classed, together 

 with the Keefer sandstone, as the McKenzie formation by the United 

 States and the Maryland geological surveys. The fossils determined by 

 Ulrich from the fossiliferous beds of this horizon opposite Great Cacapon 

 are as follows : 



Dalmanella postelegantula 



Trematospira n. sp. (near T. camura and T. perforata) 



Whitfieldella n. sp. (near W. nitida) 

 Spirifer n. sp. (near 8. sulcatus) 

 spirifer cf. eriensis 

 RhynclioneUa formosa 

 Bliynchonella cf. vellicata 

 Rhynchonella n. sp. (very finely plicated) 

 Vnicunulus cf. pyramidatus 

 Ctenodouta n. sp. 



Cleidophorus cf. Nucula sinuo-sa Simpson 

 Prothyris n. sp. and other peleeypods 

 Coleolus sp. under. 

 Othocrras. 2 species under. 

 Bcijricliia moodeyi 

 Kloedenia cf. susse.rensis 



Two undescribed species of Kloedenella and prenuntial varieties of 

 K. pennsylranica, K. turgida. and E. elarkci. 



u Clarke and Ruedemann have identified Pterygotus and Dolichopterus ? comparable 

 to D. otisius, and carapaces suggesting Hughmilleria. 



