64 



as a rule are rare. Spirifer mucronatus ( Conr.) occurs in the 

 upper portion, and with it a number of other Hamilton 

 fossils, all of which, however, have been found in 

 true Marcellus shales. Lower down, the characteristic 

 Marcellus and Genesee pelecypod Lunulicardium fragile 

 Hall appears, and with it its constant associate, the 

 minute pteropod Stvliolinn fissurella (Hall). The eminently 

 characteristic Marcellus fossil Liorhynchiis limitaris (Conr. ) 

 is sparingly represented in the lowest beds. Some little 

 distance below the mouth of Aver\''s Creek, the Strophalosia 

 bed appears in the bank again, and with it the overlying 

 lower Pleurodictyum or Nautilus bed. Both beds gently 

 descend towards the south, until near the end of the section, 

 they pass below the lake level. 



This portion of the cliff affords a good opportunity 

 for collecting the fossils from these beds, especially the 

 Nautilus magister Hall. Specimens of the latter were 

 forraerlv obtained in numbers on the beach at the foot of the 

 cliff, and the supply is probably still a fairly good one. 



North of the mouth of Avery's Creek the cliff rises to a 

 height of something over thirty feet, a portion of it project- 

 ing out into the water, so that one can not pass along the 

 beach for any distance. At the northern end of the section, 

 however, one can descend in a dr\' ravine* to the beach, and 

 walk southward along the beach to the projecting point. 

 The Strophalosia and Nautilus beds are seen everywhere in 

 the section near the top of the cliff, forming together a band 

 about a foot in thickness. The beach is strewn with the 

 fragments of these beds which have fallen from above, and a 

 good collection of the specimens may be obtained with little 

 labor. Pleurodictyum is especially abundant, the spe- 

 cimens usually being free from the matrix. The cliffs 

 are very picturesque, and present good examples of wave 

 and frost erosion. All the lower portion of the cliff consist 



•Marked "Davis" on Plate V. of the Geol. Rep't 4th District, 1843. 



