no 



CAPPS: AGE OF THE LAST GREAT GLACIATION 



Peat 7 . 

 Volcanic Ash 2. 



Peat iZ 



sunshine, the Hght, fluffy waste from the peat acting as an 

 effective insulator. Even the surface moss was sohdly frozen 

 at a depth of 6 inches in early July. The cut bank, therefore, 

 shows generally a nearly vertical peat face, and erosion takes 

 place by the formation of great vertical cracks through the 

 peat, and the falhng outward of large, tree covered blocks which 

 tumble down to the stream level and are gradually thawed and 



removed (fig. 4) . An 

 examination of this 

 section at once sug- 

 gested that if the 

 rate of accumulation 

 of the peaty mate- 

 rial could be deter- 

 mined, then a fairly 

 accurate estimate 

 could be made of 

 the length of the 

 time period whch 

 has intervened be- 

 tween the final re- 

 treat of the ice from 

 this locality and the 

 present. 



The peculiar ap- 

 pearance of the roots 

 of the spruce trees 

 which grow on the 

 edge of the bluff, as 

 well as of the stumps 

 which make up a 

 considerable portion 

 of the peaty deposit, 

 suggested that it 

 might be possible to 

 determine approxi- 

 mately the rate of 



Glacral Till 



Fig. 1. Diagrammatic section of stream bluff on 

 White River, showing relations of glacial till, peat, 

 and volcanic ash. The process of peat deposition is 

 still going on at the surface. A, a normal spruce 

 stump with flat root base, growing on solid ground. 

 B, a spruce stump growing on rapidly accumulating 

 peat. Below the line of ground frost, which rises 

 with the growth of peaty material, the roots cease to 

 unction, and the tree is forced to throw out additional 

 oots in the unfrozen surface portion of the ground. 



