564 



APPENDIX. 



28. Perrnian 



29. Coal-measures 



30. Carboniferous Limestone 



31. Lower Limestone Shale, 



etc. . 



32. Devonian Beds and Old 



Red Sandstone . 



33. Upper Silurian 



34. Lower Silurian 



35. Cambrian 



36. Fundamental Gneiss 



:} 



PERMIAN. 



CARBONIFEROUS. 



DEVONIAN & OLD 

 RED SANDSTONE. 



SILURIAN. 



CAMBRIAN. 

 LAURENTIAN. 



PRIMARY 



OR 



PALAEOZOIC. 



Note B. 



PLATE D. — Map of Europe at the Climax of the 



Ice Age. 



This map stows the centres of local glaciation, and the area covered by 

 the northern mer de glace at the climax of the Glacial Period. For the 

 line indicating the southern limits reached by this ice-sheet I have taken 

 the boundary of the " Northern Drift and Erratics," as defined by Murchi- 

 son and his colleagues, with a few modifications adopted from the map of 

 " Europa wahrend der beiden Eiszeiten," by H. Habenicht (Petermann's 

 GeograjMsche Mittheilungen, 1878). The thin red lines are intended to 

 represent the principal directions followed by the superficial strata of the 

 mer de glace. These, as a rule, corresponded with the trend of the lower 

 strata also, but now and again, owing to the form of the ground and other 

 causes, the ice at the bottom was impelled out of the course pursued by 

 the strata at a higher level. I have given in the text (p. 203) an example 

 — the long red arrows that radiate from Christianiafjord being the inferred 

 directions followed by certain erratics derived from that region. 



Mention has been made of the fact that Scandinavian erratics occur 

 in the boulder-clay of Saxony, and since this last is a true moraine profonde, 

 it follows that the erratics in question must have been dragged over the 

 bed of the Baltic and across the low grounds of Germany before they 

 could have reached their present position. Again, at Lyck in East Prus- 

 sia, at Trebnitz and Steinau in Silesia, at Meseritz in Posen, and at Ber- 

 lin, we find fragments of Silurian rocks which are recognised as having 

 come from the island of Gottland in the Baltic. All these might quite 

 well have been rolled forward under one and the same ice-sheet, but how 

 are we to account for the presence in the boulder-clay of Groningen in 

 Holland of boulders of the same rocks ? It is evident that these last 

 must have come down the basin of the Baltic and crossed the route fol- 

 lowed by the others nearly at right angles. Nor are these cases altogether 

 exceptional, for we learn that erratics from Esthonia have been detected 

 in boulder-clay at Hamburg, and that fragments derived from the island 

 of Oland are met with in the till of Faxo in Denmark. The probable 

 routes followed by these erratics are indicated by the long continuous blue 



