EARLY MAN IN SCOTLAND 133 



alluvia. When found in those regions out of Scotland, they 

 occurred in caves chiefly, and sometimes in the stratified 

 deposits which here and there underlie the upper boulder 

 clay and its accompanying gravels. 



So far as Scotland is concerned, one must look for a 

 period subsequent to the melting of the second great ice 

 sheet for evidence of the existence of early man. After its 

 disappearance important fluctuations in temperature and in 

 the relative level of land and sea took place from time to 

 time, so that the climate and the area of land in Scotland 

 differed in some measure from what is known at the present 

 day. Eventually a period of cold again occurred, not so 

 severe, undoubtedly, as in the two preceding glacial epochs, 

 but sufficient to bring into existence considerable district ice 

 sheets and extensive valley-glaciers in the Highlands and 

 Southern Uplands. Scotland at this stage was partially 

 submerged, and many of the Highland glaciers reached the 

 sea and gave orgin to icebergs. The submergence slightly 

 exceeded 100 feet, and the marine deposits formed at the 

 time are charged with arctic shells and many erratic blocks 

 and debris of rocks. On a subsequent elevation of the land, 

 the beach formed at this level constituted a terrace, well 

 marked on the coast line in many districts, and now known 

 as the loo-foot beach. 



There is good reason to believe that the elevation re- 

 ferred to was of sufficient extent to join Britain again to the 

 Continent. It is to this stage that the great timber trees 

 which underlie the old peat bogs of Scotland are referred. 

 The peat with its underlying forest bed passes out to sea, 

 and is overlaid in the carse lands of the Tay and the Forth 

 by marine deposits, which form another well-marked terrace, 

 the 45-50 foot raised beach of geologists. 



Thus the elevation of the land that followed after the 

 formation of the zoo-foot beach coincided with an 

 amelioration of climate and with the presence of an abundant 

 vegetation, and large mammals, such as the red-deer, the 

 elk, and the Bos primigenins roamed through the woods. 

 While these conditions obtained partial submergence again 

 ensued, and the sea rose to 50 feet, or thereabouts, above its 

 present level. Within recent years it has been shown that 



