of the Paleozoic Outlier of Lake Timiskaming. 301 



Paleozoic floor was considerably over 200 feet at this 

 place. 



Brisseau island, just north of Bryson, shows Ordovician 

 beds dipping away from the island on all sides from a 

 nucleus of Precambrian quartzites which outcrops on the 

 northeast corner. The relief indicated is over 50 feet. 

 At many other places these irregularities of the Paleozoic 

 floor are quite evident, the character of the floor being 

 similar to what has been reported from other districts of 

 the Laurentian shield where the contact of the Paleozoic 

 and Precambrian rocks has been studied. 



The Paleozoic Formations of Lake Timiskaming. 



Middle Ordovician: Haileybury formation. — The mid- 

 dle Ordovician in the Lake Timiskaming district is repre- 

 sented by rocks of Trenton age that are here called the 

 Haileybury formation. From a diamond drill core ob- 

 tained from west of Haileybury, the thickness of the whole 

 formation is about 250 feet. In this diamond drill core, 

 at the base of the Paleozoic there are 50 feet of red clay 

 and shales resting on the Precambrian. This red mate- 

 rial is thought to represent the reworked material of the 

 old regolith encountered by the advancing sea and rede- 

 posited on protected portions of the Paleozoic floor. It is 

 therefore only under exceptional conditions that the red 

 clay has been preserved and it is now met with in but a 

 few places. For the most part, the Haileybury forma- 

 tion begins with conglomerates and sandstones resting 

 unconformably on Precambrian rocks. The conglomer- 

 ates and sandstones are in the nature of a tangential de- 

 posit and therefore hold different time relations in the 

 various places of their occurrence. As the sea advanced, 

 the lower depressions were first filled by sediments, and 

 later the transgression over the higher knobs and ridges 

 resulted in the deposition of conglomerates at the base 

 which are higher stratigraphically than those deposited 

 on the lower parts of the old floor. The sandstones, which 

 are coarse in the basal beds, or just above the conglomer- 

 ate portion of the formation, grade upwards into finer 

 calcareous sandstones, and these in turn are followed by 

 red, green, and gray shales. The top member of the 

 Haileybury consists of 40 feet of slightly magnesian lime- 

 stone, and it is in this zone and as well in a few feet of the 

 lower shales that most of the fauna was found. 



