104 ROYAL SOCIETY OF CANADA 



low cliffs, of from. 10 to 40 feet in height. As to the general character 

 of the sandstone, Murray says, '"' The rock is for the most part of red 

 and greenish colours, generally fine grained, having pebbles of opaque 

 white quartz distributed scantily and irregularly through it. At some 

 parts it is of a pale greenish colour, striped with reddish or yellowish 

 layers, and at others it is a nearly pure white, fine-grained siliceous 

 sandstone. Some portions also are bright red and very ferruginous^ 

 and others are a coarse quartz conglomerate.'' 



The sandstones are frequently penetrated by cylindrical mark- 

 ings which are probably the Scolithus linearis of Hall. Capping the 

 sandstone directly a few feet of a green marly rock occurs, which passes- 

 directly upward into the limestones, which are frequently dolomitic 

 and form a lithographic stone. These form escarpments of fifty or 

 more feet in height and surround the entire south half of the lake,, 

 where they are capped by the characteristic massive limestones of 

 Black Eiver age with fossils of that formation. These massive beds- 

 occur at about 100 to 150 feet from the base of the limestone series- 

 There is no trace of the Calciferous in this direction nor of the Chazy 

 formation unless, indeed, certain beds of the lower portion of the 

 limestone formation may be assigned to that horizon, which in view 

 of the fossil determinations in similar limestones and shales near 

 Kingston does not now seem to be possible. 



Simihir conditions as to deposition of the Potsdam sandstone 

 and the overlying limestone formation are also to be seen at the south 

 end of Knowlton lake further to the west where also the surface of 

 the red sandstones is marked by the occurrence of sub-globular, con- 

 cretionary ferrugino-arenaceous masses, sometimes as large as an 

 orange, but oftener about the size of a walnut, giving the surface a 

 mammillated structure. In the overlying limestones at the base the 

 small fossil Leperditia is in places quite abundant. 



The most westerly of these contacts is seen along the line of the 

 Kingston and Pembroke railway about two miles north of Harrowsmith 

 station. Here the crystalline rocks, for the most part granitic, are 

 well exposed to the east of the railway and are capped by a few feet 

 only of red and green sandstone. These are overlaid by a small thick- 

 ness of green marly shales which constitute the base of the limestone 

 escarpment; the position of all the beds throughout, from the base of 

 the sandstones to the top of the limestones is uniformly nearly hori- 

 zontal, and nowhere is there any evidence of unconformity between 

 the two series though the Calciferous and Chazy formations are absent. 



The principal point at issue in the study of these contacts as 

 shown on the two sides of the Archaean axis of the Brockville-KiDgston 

 area is the difference in the relative succession of the several forma- 



