Environs of Kingston, Ont. 111 
Black River, and are probably contemporaneous with the 
upheaval of the Laurentian strata. 
-POTSDAM SANDSTONE. 
On the banks of the Rideau Canal the Potsdam sandstone 
is first met with about five or six miles to the eastward of 
Kingston Mills, and is here of suitable quality and in ample 
quantity for building stone. On the south side of Pitts- 
burg, opposite Howe Island in the St. Lawrence between 
‘Kingston and Gananoque, and again at the lower end of 
that island, it is once more seen, whilst at Gananoque it 
forms the eastern bank of the ravine near the village and 
both banks of the river Gananoque immediately in the 
village. Judging from the soundings made by me, it, 
likewise, forms the bed of this stream and extends outwards 
some distance under the St. Lawrence. The stone is used 
with very good effect in Gananoque for building purposes. 
Hay Island, Tidds Island, part of Round Island, and the 
upper end of Wellesly Island at the Thousand Island Park, 
also belong to this formation. There are thus exposures of 
the Potsdam sandstone at intervals to within six miles of 
Alexandria Bay, and as the same rock reappears near there 
and continues again at intervals to Brockville, there is a 
probability that in earlier times it has had a very much 
more extensive development in the valley uf the St. Law- 
rence here, possibly, originally, bridging over the present 
Laurentian break. 
BLAOK RIVER ROCKS. 
The city of Kingston itself is underlaid by the Black 
River limestones, these in turn resting directly on the 
Laurentian strata, as is well illustrated on the Fort hill, 
Cedar Island, the banks of Haldimand Cove and elsewhere. 
These Black River strata, underlying and around the city, 
are somewhat deficient in fossils, and at the time of publi- 
cation of Sir William Logan’s General Report on the 
Geology of Canada in 1863, considerable doubt was enter- 
.tained as to whether these rocks, in, at least, their lower 
portion, might not belong to an earlier epoch. My own 
