598 THE IGV AGE IN NORTH AMERICA. 



rim of the whole had become frozen, and so capable of re 

 taining its form. 



Similar deposits of peat in superficial kettle-holes are very 

 frequent in the glaciated region, and constitute an important 

 portion of the reserved stores of fuel laid up for the future 

 use of man. Professor Lewis and myself had an excellent 

 opportunity to study such a modern deposit at Freehold, 

 Warren county, Pa.* Here one half of such a hole had 



Fig. 152.— Section of kettle-hole in Freehold, Pennsylvania. (See text.) 



been removed in making a road, and exposed a complete 

 and fresh section through the middle. The depth of the 

 peat in the middle was six feet, growing gradually thin- 

 ner in each direction toward the sides. Peat and soil were 

 mingled in alternate layers near the edges. Numerous logs 

 of prostrate trees were also imbedded in the peat. It is 

 evident that had there been a readvance of the ice over this 

 region after the above accumulation was complete, and had 

 the soil become frozen, there would have been at Freehold 

 an interglacial deposit of vegetable matter closely analogous 

 to that described at Germantown. 



A comparatively short interval between the periods of 

 recession and advance of the ice-front in southern Ohio is 

 also indicated in numerous places where fragments of wood 

 are found imbedded in true glacial deposits near the glacial 

 margin. For example, near Darrtown, on Four- Mile Creek, 

 in Butler county, Ohio, is an exposure of till, sixty-five feet 

 high, containing fresh red-cedar logs near the bottom, and 

 fragments of wood in all conceivable positions throughout 

 the lower half of the deposit. The deposit is true till, being 

 tmstratified and full of scratched stones, many of which are 

 granitic. There is, however a line of stratified material 



* S^e " Second Geological Survey of Pennsylvania, Z," p. 1*71. 



