GEOLOGY OF THE AUBURN-GENOA QUADRANGLES 2g 



Cashaqua shale 



This formation was named from its favorable exposure along 

 Cashaqua creek^ one of the tributaries of the Genesee river in Liv- 

 ingston county. In that locality it is composed almost entirely of 

 hght blue gray or olive shale, but toward the east it acquires a 

 slowly increasing proportion of arenaceous matter and on this quad- 

 rangle there are frequent flags and thin sandstones, specially in the 

 upper beds where some of the latter are i to 3 feet thick and 

 usually schistose to a degree that makes them valuable for flagging, 

 for which purpose they have been extensively quarried on both sides 

 of the Cayuga lake valley. 



Except that the shales in the lower part of the formation are 

 rather less calcareous here than they are in the Genesee valley they 

 are of much the same appearance and character. 



The upper limit is at the top of a band of soft dark shale about 

 265 feet above the base and approximately, at least, in the horizon of 

 the Rhinestreet shale that contains a few small lamellibranchs like 

 those below and is succeeded by more arenaceous sediments that 

 carry an abundant brachiopodous fauna. 



The Cashaqua beds are exposed in the ravines between Heddens 

 and Clearview and similarly on the opposite side of the lake, also 

 farther north in the Trumansburg and Taghanic creek ravines. The 

 upper flaggy beds are displayed in a number of large quarries now 

 mostly abandoned between Taghanic Falls and Ovid Center, also at 

 Goodyears and King Ferry. The lower beds appear in the ravines 

 on the east side of the Salmon creek valley north of Genoa and along 

 the west branch of Salmon creek in the vicinity of Little Hollow. 



Fossils. The lower soft shales contain, though not abundantly, 

 some members of the characteristic fauna of the Cashaqua beds 

 farther west, viz : 



Pterochaenia fragilis (Hall) Spirifer laevis Hall occurs at Tag- 



Buchiola retrostriata (von Buck) hanic Falls near the top of ihe 



Probeloceras lutheri Clarke lower beds 

 Bactrites aciculum (Hall) 



A thin layer of soft sandstone 35 feet higher exposed in Hunt's 

 quarry i^ miles southeast of Interlaken contains: 



Spirifer rnesacostal's Hall Conularia cf. continens Hall 



Productella spinulicosta Hall Helianthaster gyaluni Clarke 



Camarotoechia congregata (Conrad) Stictopora 



Chonetes lepidus Hall Melocrinus sp. 



Palaeoneilo constricta (Conrad) Plumalina 

 Leptodesma sp. 



