PORTAGE AND NUNDA QUADRANGLES 157 



gorge is made dark and rusty by the ferruginous characters of the 

 coarser shales and sandstones. 



The flags in these beds are smooth and even on the lower surface 

 except for the presence of casts of depressions in the soft mud 

 beneath, on which they were deposited in the shape of short 

 straight ridges lying at all angles. These bodies have been known 

 as Fucoides graphic a. The upper surface of the flags is 

 usually shaly. Fossils except plant remains are very rare, though 

 some of the lighter colored shales in the lower part contain : 



Manticoceras pattersoni (Hall) Ontaria suborbicularis (Hall) 



Probeloceras lutheri Clarke Palaeotrochus praecursor Clarke 



Orthoceras pacator Hall Buchiola speciosa (v. Buck) and a 

 Phragmostoma natator Hall few other forms. 



Besides the exposure of these Hatch beds for 8 miles in the cliff 

 along the river from opposite Gibsonville to the mouth of Wolf 

 creek, they may be seen along the Silver lake outlet 2 miles below 

 Perry; in the upper part of the ravine 2 miles northwest of Mount 

 Morris ; along Buck run above the falls to the first highway bridge ; 

 on Cashaqua creek and at Tuscarora a mile below ; also in the 

 ravines at West Sparta and in nearly all of the ravines on the east 

 side of the Canaseraga valley within the limits of the Nunda quad- 

 rangle. 



Grimes sandstone 



At the mouth of Wolf creek a band of thin sandstones separated 

 by hard dark shales, altogether about 25 feet thick, overlying the 

 Hatch flags and shales comes down to the bottom of the cliff. It 

 is 60 to 85 feet from the base of the cliffs at the east end of the 

 St Helena bridge and is prominent in the eastern rock wall opposite 

 the Gardeau Flats, 1 to 2 miles below St Helena. 



It is here essentially barren except for plant remains, and it is 

 not a very well defined nor significant feature of the Portage section 

 on the Genesee river or further west, but toward the east in the 

 Springwater and Naples valleys the sandstones are much heavier 

 and contain brachiopods and other forms not found in the Portage 

 beds of the western part of the State, though most of them are 

 common in the " Ithaca " beds of this horizon and that of the 

 Hatch flags and shales in Tompkins county and farther east. 



At Naples the characteristic lamellibranchs and many of the other 

 forms composing the Naples fauna that occur more or less abund- 

 antly up to the base of this band have not been found above it. 



This formation was first described as a member in the Portage 



