5o6 



PRINCIPLES OF STRATIGRAPHY 



accompanying changes in physical outHne of Great Britain. His 

 succession of late glacial and interglacial stages in Scotland is as 

 follows : 



5. Upper Turbarian or Sixth Glacial Stage. 



High-level corrie glaciers, with snow line at 3,500 feet; peat overlying 

 Upper Forest; raised beaches at 25 to 30 feet; somewhat cold and wet 

 climate. 



4. Upper Forestian or Fifth Interglacial Stage. 



Upper Forest overlying lower peat; relatively dry and genial climate; 

 land area somewhat more extensive than now. 



3. Lower Turbarian or Fifth Glacial Stage. 



Valley-glaciers, with average snow-line at 2,400 to 2,500 feet; Lower 

 Peat overlying Lower Forest; raised beaches at 45 to 50 feet; cold and 

 wet climate. 



2. Lower Forestian or Fourth Interglacial Stage. 



Lower Forest overlying morainic accumulations of Fourth Glacial 

 stage; genial climate; land area of greater extent than now. 



I. Mecklenburgian or Fourth Glacial Stage. 



District ice-sheets and large valley glaciers of Highlands and Southern 

 Uplands; raised beaches at 100 to 135 feet; Arctic climate, with snow- 

 line ranging from 1,000 feet in west and northwest to 1,500 feet or 

 thereabout in Central Scotland. 



The typical succession of strata of the Scottish peat bogs agrees 

 with this series of changes, this being as follows : 



