OF CENTRAL CANADA PART III. 207 



similar warin-sea mollusca, but these strata contain also many palm- 

 fruits, with the remains of large ophidians, and the teeth and bones 

 of large mammals allied to the existing tapir, rhinoceros, hippo- 

 potamus and other genera, now limited, or nearly so, to intertropical 

 habitation. As time passed on, however, a great climatic change 

 appears to have crept slowly over all the northern portions of both 

 the eastern and western continents, and to have been experienced 

 also in the extreme south. Under its influence, the once warm 

 climate gradually gave place to all the rigours of an Arctic winter. 

 This remarkable change was evidently accompanied, and probably in 

 chief part produced, by great alterations in the previously-existing 

 levels of land and sea. All the higher lands appear to have been 

 covered by broadly-extended glaciers, whilst the seas were traversed 

 by floating icebergs, bearing southwards the boulders and detritus of 

 northern rocks. This condition of things was undoubtedly of long 

 duration. Between its close and the actual commencement of the 

 natural conditions now existing, no strict demarcation can be drawn. 

 The one period merged slowly into the other, as the glacial mani- 

 festations were gradually beaten back to within the higher latitudes 

 and alpine elevations in which they still prevail. Deposits of this 

 glacial period are present almost everywhere throughout Ontario 

 and Quebec. (See Part Y.) 



(10). At some remote epoch of this later time, Man appeared 

 upon the scene, His advent preceded the extinction of several im- 

 portant species and even genera of mammals \ a fact which in itself 

 goes far to prove the high antiquity of our race. The extinction of 

 these types cannot be supposed to have taken place in any sudden 

 manner, but was undoubtedly the result of slow organic and physical 

 changes, proceeding continuously throughout long intervals of time. 

 All the earlier tokens of man's presence on the earth the rude flint 

 and bone implements found in certain gravel-beds, associated in 

 places with extinct mammalian remains indicate a low state of 

 civilization ; a deduction sustained to some extent by the characters 

 of certain human crania found in similar deposits. In later accumu- 

 lations of detrital matter, as well as in many peat-morasses, etc., 

 somewhat more finished types of stone utensils and weapons make 

 their appearance ; and these become replaced, in higher portions of 

 the same deposits, by characteristic memorials of the so-called bronze 

 and iron periods. 



