different beds of the marine Richmond and the Lorraine 

 are not very persistent; in consequence, it is somewhat 

 difficult to correlate the strata of different exposures. 

 The most continuous layer is a heavy bed of limestone 

 with numerous bryozoa which lies near the base of the 

 Richmond. 



A cliff of about 25 feet (7-6 m.) of limestone and 

 shale is presented by the scarped bank of the river near 

 the bridge to the northward of Streetsville Junction. The 

 lower portion only is actually exposed and shows the heavy 

 bryozoan layer of about two feet in thickness. Beneath 

 this are thin-bedded limestones and shales, which may 

 belong to the Richmond or to the underlying Lorraine. 

 This is one of the best localities for collecting the typical 

 stromatoporoids and corals: 



Stromatocerium huronense Billings. 

 Columnaria alveolata Goldfuss. 

 Columnaria calicina {Nicholson) . 

 Streptelasma rusticum {Billings). 

 Tetradium minus Safford. 



Just below this point an interesting minor anticline 

 is shown: the heavy bryozoan layer forms the surface 

 rock, but it is covered by three feet of boulder clay con- 

 taining pebbles and also corals and stromatoporoids of 

 the local formation. The northeast side shows glacial 

 grooving and polishing, but the southwest side is much 

 less affected by the passage of the glacier. 



The upper limestones, shales and coral reefs are ex- 

 cellently exposed at several points on the west side of the 

 river above the bridge. Besides the stromatoporoids and 

 corals an abundant fauna is presented, of which the follow- 

 ing are the more common species: — 



Callopora sp. 



Prasopora cf. hospital s {Nicholson) . 



Rhombotrypa quadrata {Rominger). 



Catazyga headi {Billings). 

 Hebertella occidentalis {Hall). 

 Platystrophia biforata (Schlotheim) . 

 Platystrophia laticosta {Meek^. 

 Platystrophia clarksvillensis Foerste. 



