25 6 PREHISTORIC EUROPE. 



the conditions which obtained during the accumulation of the 

 older boulder-clay — a period of intense arctic rigour, when the 

 country was buried in ice to a depth in the Lowlands of 3000 

 feet or more. Then we have to think of the time required for 

 the gradual change of climate which brought about the dissolu- 

 tion of that enormous mass of ice, and the long lapse of ages 

 involved in the slow advance, first of an arctic and boreal and 

 then of a more temperate flora, before the land was fitted to 

 support the large mammals whose relics have come down to us. 

 Lastly, we have to reflect that these temperate conditions must 

 have continued for some period more or less prolonged before 

 the climate again began to cool down to such an extent that 

 snow and ice eventually resumed their empire, and a mer de 

 glace, little less extensive than the. first, drowned the mainland, 

 filled up the adjacent seas, and overflowed the islands of the 

 Outer Hebrides. 



To illustrate these remarks I may describe a section at 

 Hailes Quarry, two miles west of Edinburgh, to which my 

 attention was called by Dr. Croll. This section was well ex- 

 posed in 1878 when I visited it, but I have not seen it since. 

 On the 9th July of that year the general succession of the 

 deposits was well shown in one part of the quarry, of which I 

 took the following sketch (Fig. 7). The lower boulder-clay (1) 

 was the usual blue, hard, tough till commonly met with in the 

 district. Above it came an irregular bed of coarse earthy 

 and gritty sand (2), with a few large boulders of dolerite which 

 were most numerous at and near its upper surface. Besting 

 upon this bed was a layer of peat (3), varying from an inch to 

 a foot or eighteen inches in thickness. It contained many frag- 

 ments of wood — sticks, roots, etc., of what appeared to be 

 principally birch. I detected some wing-cases of small beetles, 

 but unfortunately they had crumbled to dust when I got 

 them home. Mr. Bennie, however, afterwards obtained many 

 more, amongst them being one of Geotrupes stercorarius, 

 as determined by Dr. Purves. Above the peat came a 

 bed of pale blue sandy clay from two to four inches (4), which 



