42 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VI. 
lower level than the Iroquois beach,* though up to the present no 
marine shells have been found on these lower beaches. 
AGE AND CONDITIONS OF THE IROQUOIS BEACH DEPOSITS. 
Judging from the apparent maturity of the Iroquois beach as 
compared with that of Lake Ontario, one may suppose that the two 
beaches required about equal times for their production. If this be 
admitted, and if it be assumed that the Iroquois beach was begun at 
about the time Niagara Falls commenced its work, we may conclude 
that the waters retired from the Iroquois level about midway between 
the time of the retreat of the ice from the western end of the Ontario 
basin and the present. As this time is variously estimated at from 
5,000 to 30,000 years or somewhat more, the Iroquois beach was 
probably abandoned from 2,500 to 15,000 years ago. Dr Spencer in 
conversation hase xpressed a belief that the beach is 17,000 years old, 
and this estimate may be looked on as representing the extreme limit 
ofits age. It is possible that a more direct estimate of the time which 
has elapsed since the Iroquois water was drained may be made in the 
future, based for instance, on the present rate of erosion of the Scarboro’ 
shore, or on the cutting of the Don or Humber valleys, and some 
observations and photographs have been made to serve as a starting 
point for such an investigation, but results that are of value have not 
yet been obtained. 
The climatic conditions of the time were probably more rigorous 
than the present, though exact data to settle the point are not available. 
The two trees determined by Professor Penhallow, tamarack and spruce, 
belong on the whole to a relatively cool region, but both extend farther 
south than Toronto at present. In any case they appear to belong to 
an earlier time than the Iroquois beach, since they underlie its gravels. 
The caribou and elephants of the bars near Toronto suggest a dis- 
tinctly colder climate than the present though not necessarily a glacial 
one ; but there is not much in the structure of the beach itself to point 
in the same direction. Large boulders that might have been rafted by 
shore ice or carried by bergs have nowhere been found in the Iroquois 
deposits near Toronto. There are however, some crumpled beds of 
sand lying between horizontally bedded layers, which may have 
resulted from the grounding of ice floes ; but it is not impossible that ice 
floes thirty-two inches thick, such as formed on Lake Erie last winter, 
may produce similar effects on beds of sand or clay along the shores of 
our present lakes when driven by violent storms. 
Though the Iroquois climate was probably distinctly colder than that 
* A Short History of the Great Lakes, Frank Bursley Taylor, 1897, p. 18. 
