R. Damon—" The Great Northern Drift:' 403 



on the Observatory Hill is about 56 feet above the present river level. 

 The Castle Hill, which is partly natural, partly artificial, has at its 

 base another bed, whose level I was unable to ascertain accurately ; 

 this probably belongs to the Chesterton gravel. Jesus College stands 

 on gravel at a lower level still, while the base of the Barnwell bed 

 is at a height of sixteen feet above the river level. Thus we have 

 four distinct terraces, unless the Jesus College bed forms part of the 

 Chesterton series, which is improbable. 



I must express my thanks to Mr. 0. Fisher, M.A., and Prof. 

 Hughes, for the encouragement and help they have given me in the 

 preparation of this brief notice. My thanks are also due to Mr. 

 Haddon, of Christ's College, for his kindness in making drawings of 

 the implements for me.^ 



Cheist's College, June, 1878. A. F. Griffith. 



V. — Wayside Notes in Travels over Europe. — The Great 



Northern Drift. 



By EoBERT Damon, F.G.S. 



THE overland route to Eussia via Konigsberg or Warsaw — now 

 accomplished with comparative ease — reveals some instructive 

 facts connected with one of the most recent yet extreme of 

 climatal changes which has contributed to mould and fashion so 

 large a portion of the surface geology of Northern Europe. I refer 

 to the "Great Ice Age," or "Glacial Period," when a frozen sea 

 probably covered the extensive plains now known as Russian Poland. 



Soon after leaving the German frontier, granitic debris and small 

 stones everywhere appear on the surface. These granitic erratic 

 boulders, for such they really are, increase in number and dimen- 

 sions as the journey is pursued, so that in a few hours they have so 

 augmented that a considerable distance might be traversed by stej)ping 

 from one of these stones to another. Now and then there are some 

 one or more of exceptionally large proportions, but taken as a whole, 

 the increase in size is extremely uniform, and before the environs of 

 St. Petersburg or Moscow is reached, many of them attain colossal 

 dimensions. Having in my recollection the block of granite in the 

 Admiralty Square in St. Petersburg, on which stands the equestrian 

 statue of the Czar Peter, many of the boulders referred to are 

 hundreds of tons each in weight. In some instances the railway 

 has paid respect to their dimensions and avoided them, for no 

 ordinary mechanical power could effect their removal. As may be 

 expected, their size increases as their source is approached, though on 

 sea-beaches the larger pebbles are carried the furthest because they 

 are said to offer a larger surface for the moving force to act upon. 



It requires but little penetration to discern that the direction of 

 the transporting power by which this vast mass of erratics has been 

 sown broadcast over the central plain of Europe, has acted from N. 

 or N. E. to S. and S. W. Several specimens of granite gneiss, etc., I 



' These are not reproduced here, it heing believed sufficient to refer the reader to 

 Dr. John Evans's work. — Edit. Geol. Mag. 



