-14- 



12.35 00.25 View of the cement quarry on the left. Bridge over 

 Bailey Creek. 



12.45 00.10 Concrete bridge over railroad. 



13.25 00.80 T-road. SLOW. Turn left into private road along edge of 

 bluff of Vermilion River. On the left, the south working 

 face of the Marquette Cement Manufacturing Company quarry 

 can be seen. The uppermost ledge represents the Little 

 Vermilion Limestone Member of the Pennsylvanian Bond 

 Formation. 



13.75 00.50 Turn left and park in gravel pit stockpile area. The 



walk to the Bailey Falls locality (fig. 6) will be approx- 

 imately a quarter of a mile and, except where a gravel pit 

 intersects the road, will be an easy hike. Returning is 

 a different matter. If you collect heavily, please ask 

 assistance in carrying your samples. 



STOP NO. 2, BAILEY FALLS. SE^ NW% Sec. 6, T. 32 N., R. 2 E., La Salle 

 Quadrangle . 



The entry road formerly continued parallel to the Vermilion River as 

 far as Bailey Falls. It is now interrupted by a gravel pit. After crossing 

 the pit, you will find that the road continues on the downslope side. Bailey 

 Falls is identified by a partially ruined picnic shelter, a limestone cliff, and 

 a jumble of large limestone blocks that have been undercut by Bailey Creek. 



The cliff and jumbled blocks are DANGEROUS. PLEASE DO NOT STAND 

 NEAR THE EDGE OR UNNECESSARILY LONG BENEATH THE CLIFF. The La Salle Member 

 of the Bond Formation forms the cliff (figs. 8 and 9). It is underlain by 

 black and gray shale which forms the immediate banks of Bailey Creek. At 

 the mouth of the creek, the Hall? Limestone Member forms a low waterfall. 

 In addition to natural assemblages (figs. 7 and 10), discrete conodonts 

 have been found in virtually every part of the section. Merrill has col- 

 lected faunas in abundance from all of the limestones as well as from one 

 shale (table 1) and has recognized four distinct biofacies in this section. 

 Bed 9 of figure 8 contains important Cavusgnathus ( Adetognathus of Lane 

 [1967], and other authors) and is referred to as the Cavusgnathus biofacies. 

 The biofacies is interpreted as characteristic of nearshore environments 

 and significant for biostratigraphic subdivision only in that it tends 

 to dilute the short-ranging gnathodid populations in some faunas. 



Beds 10, 11, and 12 (fig. 8) have yielded an Appalachian bio- 

 facies fauna. The Appalachian biofacies is dominated by Strep tognathodus 

 and is made up of species that have been used for zonation of the Conemaugh 

 Group in Pennsylvania (Lane, Merrill, Straka, and Webster, 1971, fig. 4, 

 p. 409). The Conemaugh zonal species Streptognathodus elegantulus , S_. 

 gracilis , S_. appletus , and S_. cancellosus all occur in beds 9, 12, and 13. 



Bed 13 is of special interest in that it has an important Idiognathodus 

 population, which is indicative of older Midcontinent faunas and is there- 

 fore referred to as representing a Midcontinent biofacies (Lane, Merrill, 



