Mild Polar Climates. 285 



satisfactorily ascertained that those beds are wholly devoid of 

 such materials ? Those beds, I presume, have been searched 

 by geologists for their fossil contents rather than for strati- 

 graphical evidence of glacial epochs. It is remarkable how 

 long the evidence of glaciation sometimes remains unobserved 

 when no special attention is devoted to the matter. As 

 examples of this, we know with certainty that the Orkney 

 and (Shetland Islands were during the glacial epoch over- 

 ridden by land-ice; and yet geologists who had often visited 

 these islands declared that they bore no marks of glaciation. 

 So recently as 1875 the low grounds of Northern Germany 

 were believed to be without glacial striae; yet when German 

 geologists began to turn their attention specially to the subject, 

 they found not only evidence of glaciation but indisputable 

 proof that during the glacial epoch the great Scandinavian 

 ice-sheet had advanced over the country no fewer than three 

 separate times down to the latitude of Berlin. I have myself 

 seen the striated summit of a mountain on which geologists 

 had been treading for years without observing the ice- 

 markings under their feet. The reason why these markings 

 so long escaped detection is doubtless due to the fact that 

 they were on a spot which no geologist supposed that land- 

 ice could have reached. For this very same reason the fact 

 remained so long unobserved that the low-lying ground of 

 Caithness had been glaciated by land-ice from Scandinavia, 

 filling the entire Baltic and the North Sea. Many similar 

 cases might be adduced where the marks of glaciation re- 

 mained long unobserved, either because no special search had 

 been made for them, or because they were under conditions in 

 which they were not expected to be found. It is very probable 

 that when the Tertiary deposits are carefully examined, with 

 the special object of ascertaining whether or not they contain 

 evidence of glaciation, geologists may be led to a different 

 conclusion regarding the supposed uniformly warm character 

 of the climate of that period. They may possibly find that, after 

 all, the Tertiary beds do contain boulders and foreign material, 

 indicating the existence of glacial conditions during the period. 

 Considerable importance has been attached to the statement 

 of Professor Nordenskjold that he failed to observe in the 

 stratified deposits of Greenland and Spitzbergen any evi- 

 dence whatever of former glaciation in those regions. " We 

 have never seen," he says, " in Spitzbergen nor in Green- 

 land, in these sections often many miles in length, and 

 including, one may say, all formations from the Silurian to 

 the Tertiary, any boulders even as large as a child's head. 

 There is not the smallest probability that strata of any con- 



