PHYSICAL AND CLIMATAL CONDITIONS. I37 



been a little lower in mean teini)emlm-e, l)ut less extreme 

 than that of Xortli America at the ])resent day. It is 

 fartiier to he observed that the Pleistocene marine fanna 

 is a little less boreal in New En,L;land than in the St. 

 Lawrence valley, and that fnrther north in Hndson's 

 bay and the arctic coasts, it is not very dissimilar from 

 that of the St. Lawrence. 



In the later f^lacial period, that of the Saxicava sand, 

 the great size and wide dispersion of boulders indicates 

 much heavy field-ice, and, conse(piently, a. low temperature 

 of the sen, while the existence of hjcal glaciers on the 

 high lands not submerged, also indicates a low temperature. 

 To this corresponds the vast ])redominance of the species 

 SaA'icaca riigosa in the lower part of the Saxicava sand. 

 There would, in this period, seem to have l)een fluctuations 

 in temperature, due, perhaps to elevations and depressions 

 of land, so that while in some of the raised l)eaches tlu; 

 indications of ice-drift are not so extreme as at present, 

 on Ouher levels there are t'igantic boulders, and some 

 of these carried far. Thus the later Pleistocene was 

 characteri/ed at once by great variaticjus in the elevation 

 of the land and by corresponding vicissitudes of climate. 



These few remarks will, I think, sullice on this subject, 

 when taken in connection with the facts and principles 

 stated beforehand in chapter first. 



An interesting illustration of the effects of varying 

 distribution of land and water, may be taken from that 

 warm period already alluded to as intervening between 

 the glacial and modern times, and coinciding with the 

 second continentid period of Lyell, as evidenced by the 

 distribution of marine animals at present on the coasts 

 of Nova Scotia and New England. This peculiarity of 

 distribution attracted my attention, as a collector of 



