1893.] evidence for the Recurrence of Ice Ages. 119 



ice, and, secondly, by what means and how far may some of them 

 be handed on by other agents beyond the regions of probable ice 

 transport. 



Having thus reduced the necessary glaciation of these south 

 regions to more modest dimensions we may enquire what causes 

 may be suggested in explanation of the occurrence of greater cold 

 in those regions in former times. We know approximately what 

 increase of cold to expect as we ascend a mountain range or as a 

 mountain region is upheaved, and we know that some areas are 

 more unstable than others. What evidence have we of great 

 earth movements in the regions from which the ice-borne boulders 

 have been derived ? 



To these different but connected questions I hope to be 

 allowed to return on future occasions. 



xvii. List of Specimens exhibited in illustration of paper^. 



1. Smoothed and striated surface of Molasse in situ near the highest 

 part of Lausanne, Lake of Geneva. Collected with Professor 

 Renevier, 1873. The striee run in a north-westerly direction. 



2. Surface of solid rock glaciated. North of Killaloe, Co. Clare, 

 Ireland. 



3. Similar surface on fragment from the Olwydian Drift near Ffynon 

 Beuno, St Asaph, North Wales. 



4. Boulder of Mountain Limestone which had received polish and 

 striations and was then broken up and the fragments imbedded 

 in the later or Clwydian Drift. 



5. Piece of the polished and striated surface of the solid Portlandien 

 Rock which lay in the path of the great Swiss valley glacier 

 above the quarries, north of Solothurn (Soleure), Switzerland. 



6. Boulder of limestone with the protuberant parts polished and 

 striated, Drift, Roslyn Pit, Ely. 



7. Vein quartz smoothed, polished, and striated by glacial action. 

 Top of Slievwhuallian, Isle of Man (50 yards S.W. of fence corner, 

 S. W. of Cairn y^q). Given to me by Mr Lamplugh. 



8. Piece of Burr-stone, used in Phosphate mill. Bur well Lode, 

 Cambridge. 



9. Slickensides from fault in Lower Keuper Sandstone, Alderley 

 Edge, Cheshire. 



10. Do. from the Stockdale Shale of Skelgill, Windermere. 



11. A cluster of crystals of Calcite which have been exposed to the 

 spray from a mountain rill. Third Grit near Park House, south 

 of Wray, Lancaster. 



12. A mass of banded travertine from the side of a small stream 

 draining the peat near Big Wheel Lode, Penrhyn, Portmadoc. 



13. A similar mass which was wedged in among some insoluble 

 stones in such a manner as to be acted upon nearly all over. 

 The points of contact with the other stones remain rough like 



1 These specimens are now arranged, with corresponding numbers attached, 

 in the Woodwardian Museum. 



