39 



certain conglomerates, grits and sandstone- 

 which mark the base of the Lowville (Birdseye) 

 and Black River formations. 



Owing to inequalities of the pre-existing land 

 surface as well as to subsequent unequal erosion, 

 the present line of contact between the Palae- 

 ozoic and the Archean is very intricate. As a 

 consequence large irregular-shaped masses of 

 flat-lying Palaeozoic strata extend for many 

 miles beyond the general direction of the line 

 of junction, while corresponding insets of highly 

 inclined Archean rocks break up the continuity 

 of the main mass of the Palaeozoic rocks. 

 This irregularity in the line of division between 

 these two series of formations is further accentu- 

 ated by the occurrence of outliers of flat-lying 

 Palaeozoic rocks, some of which are now separa- 

 ated by intervals of many miles from the main 

 mass to the south. 



263 -34 m. Marmora. — Alt. 594 ft. (181 m.) 



423-8 km. 



282-92 m. Milibridge. — Alt. 944 ft. (287-7 m -) 



455 '3 km. The party will leave the railway at Milibridge, 

 and will drive up the Hastings road to Murphy's 

 Corners and thence to St. Ola station. 



Between Milibridge station and Milibridge 

 post office, the blue limestone of the Gren- 

 ville-Hastings series is excellently exposed. 

 It is well-bedded, heavier beds alternating 

 with thin beds which are usually laminated. 

 Some of these beds are more distinctly blue 

 in colour and effervesce readily when a drop 

 of diluted acid is placed on the surface of the 

 rock; others are greyer in colour and give a 

 distinct effervescence only when powdered. The 

 lamination undoubtedly represents the original 

 bedding of the rock, and while the rock in many 

 places is much contorted, the limestone still 

 retains its blue colour, showing that the alter- 

 ation has not been nearly so intense as in the 

 case of the same series further north, where 

 metamorphism has entirely dissipated the 

 colour of the limestones, producing at the same 

 time a certain coarsening in grain. 



