Marcou.J 
204 
Jan. 21, 
the water flows toward the St. Lawrence river over gray and 
black slates with thin beds of calcareous-marls interstratified now 
and then in the slates. No fossils have been found yet in those 
gray and black slates, nor in the thin beds of calcareous-marls. 
The slates dip at an angle of sixty degrees south-south-east. They 
belong to a system of strata older than the horizontal Black river 
and Trenton limestone of the top of the fall, and are similar and 
of the same age as those forming the beach of Lake Champlain 
west of Swanton’s fall, and which I have called Swanton slates ” 
of the Upper Taconic system. 
If we consider the plan of quartzites east of the fall, looking 
almost like a perpendicular wall, we see that a recession exists at 
the fall, and that constant washing and yearly frost, have eroded 
a sort of gorge. At the beginning of the modern period, just 
after the glacial epoch and the St. Lawrence Quarternary deposits 
of sand with marine shells, the Fall was exactly above the south- 
eastern limit of the quartzites, which are seen at the foot of the 
fall ; and the small basin at the contact of the slate formation and 
the quartzites is the remains of the basin made at first by the 
leaping of the river. The recession seems to be of about twenty- 
eight to thirty feet, giving a very slow rate in forming the gorge ; 
for we must consider that the age of the Montmorency fall is the 
same as the Niagara fall which had made such a long gorge during 
the same space of time. Notwithstanding many calculations 
already suggested for the recession of the Niagara fall, from near 
Lewiston to its actual position ; suggestions which have varied 
from four thousand years to three millions or even more millions 
of years, giving a wide range of speculation as to the length of 
time required ; it is impossible to give any close approximation. 
But at all events the rate of recession of the Montmorency fall 
is certainly very small, on account of the hard quartzite material 
of the fall, and of the almost perpendicular position of the quart- 
zite strata. However the recession of the fall is a plain fact, which 
is clearly seen at low water. Another important fact, is that at 
the foot of the fall there are no traces of Black river and Trenton 
limestone ; if any have ever fallen from above by landslides, 
which was very likely the case at the beginning of the existence 
of the fall, then all have been destroyed and washed away long 
before our present time. 
On the left side of the fall — or eastern side — there is a small 
