No. 3.] SPENCER — PALyEOZOrC GEOLOGY. 171 



geologically and geographically higher than at its mouth, but 

 geographically lower than the inferior beds at Dundas, on account 

 of the dip of the strata. 



The five feet of sandstone constitute the prevailing " Gray 

 Band" of the Medina formation. 



The thickness of the Medina shales appears to be 595 feet. 

 I have placed the thickness of the Medina shales at 535 feet; 

 this being derived from the record of the well at Dundas, where 

 they are underlaid by ''limestones and grit?>," whilst in the Bar- 

 ton well the red shales are underlaid by " bluish and grayish 

 shales," which probably belong to the Hudson Biver group. 



It must be remarked that the Dundas well is not far beyond 

 the turn in the bend of the Niagara escarpment, which I have 

 designated by the name of ancient Cape Dundas. In the pre- 

 vious Beport attention has been frequently called to the fact that 

 all the shaly deposits decrease, and those which are calcareous 

 increase the moment that we pass around the provisionally called 

 Cape Dundas. In proceeding northward the Medina shales thin 

 out and are last seen at Cabot's Head, and, according to Dr. 

 Bell, are entirely ab^-ent from the series in the Manitoulin Island. 

 Therefore this diiference of about 60 feet is one of thickness and 

 not of error. It was also noticed that in proceeding south-west- 

 ward towards Ohio, that the Medina shales almost entirely dis- 

 appear. 



Had I known of the existence of the well in Barton at the 

 time that I took the levels over the adjicent localities, it would 

 havo given an additional point for correcting the estimate of the 

 dip. The altitude of the place, about a quarter of a mile north- 

 east of the well, is 435 feet above Lake Ontario, while at a 

 quarter of a mile to the eastward, it is 421 feet, on a surface of 

 rocks. Calculating from these data, the dip would be between 22 

 and 27 feet in a mile, but as the well is between the.se two points, 

 we can retain our old estimate of 25.4 feet in a mile, having a 

 direction of 20 degrees west of south. 



