47 



By means of the wye level, the exact elevations of these two beds above 

 sea-level at the localities mentioned were obtained. From these observations 

 the dip was determined to be in a direction S. 26° W., at the rate of 20 feet per 

 mile. Estimates based on other distinctive beds, which could be followed down 

 the river, such as the Columnaria reef in the Meadowvale member and the heavy 

 bed of limestone in the Homotrypa streetsvillensis zone of the Streetsville member, 

 bore out the accuracy of these figures. Once the dip was determined with 

 satisfaction, the stratigraphic intervals between all the exposures on the river 

 could be calculated, as well as the intervals between them and the exposures 

 to the east and west. 



Explanation of Composite Section. — A composite section, making use of 

 these figures will be found on the folded page. All figures referring to level in 

 this section and throughout the article are not elevations above the sea, but 

 denote the position of the horizon under discussion in the above composite 

 section, the base of which is the bottom of the quarry at the mouth of the Credit 

 river (this horizon being taken as 234 feet above sea-level). 



Dundas Formation 



Humber Member 



The lower 26 feet (234 to 260) as exposed in the quarry at the mouth of 

 the Credit river at Port Credit, and for some distance above, consist of rocks 

 which are more calcareous than usual and contain very large numbers of 

 Rafinesquina mucronata torontonensis, described by Parks and Dyer from the 

 Dundas formation of the Humber river, and Zygospira erratica (Hall) from 

 the New York Pulaski. 



The following fossils were found at this horizon : — 



Stigmatella catenulata var. B, Parks and Dyer. 



Rafinesquina mucronata torontonensis, Parks and Dyer. 



Byssonychia radiata (Hall). 



Ctenodonta filistriata, Ulrich. 



Cuneamya scapha brevior, Foerste. 



Ischyrodonta cf. unionoides (Meek). 



Modiolopsis postplicata, Foerste. 



Modiolopsis concentrica, Hall and Whitfield. 



Pterinea demissa (Conrad). 



Whiteavesia pholadiformis (Hall). 



Whitella cf. hindi (Billings). 



Whitella cf. torontonensis, Stewart. 



Orthoceras lamellosum, Hall. 



Isotelus maximus, Locke. 



Glyptocrinus sp. 



Lichenocrinus sp. 



This fauna is very similar to that of the Humber River section to the east. 

 Compared with the faunas of the Ohio Valley formations, it shows a mixture of 

 typical Waynesville and Maysville types but with a much stronger leaning 

 toward the Maysville. In view of the relative paucity of species, it seems 

 impossible to correlate the strata with any of the divisions of the Maysville 

 recognized in Ohio. It is to be noted also that six out of the fifteen definite 

 species listed are unrecorded from the Ohio valley or from New York. 



For a distance of 100 feet above the top of the fossiliferous zone of the 

 Humber member, shales greatly predominate, and up to the present no fossils 

 have been found. At some localities the shales look inviting to the collector, 

 being of a rubbly or nodular character, and it was only after much searching 

 that the writer gave up hope of finding fossils. 



