122 NATURE STUDY. 



Large rivers carry down logs and drift-wood of all sorts that 

 sink or lodge against the bank when the slow water near 

 the mouth is reached, and thus begin an accumulation of 

 vegetable deposit. In 1835 Louisiana cleared out such a 

 raft that was ten miles long, seven hundred feet wide and 

 eighteen feet thick. 



The Great Dismal Swamp in Virginia and North Caro- 

 lina, forty miles long and twenty-five wide, is a typical 

 southern peat bog. In the middle is a lake of clear, wine- 

 colored water seven miles in diameter and fifteen feet deep. 

 Here, as in the case of many other peat deposits the center 

 of the swamp is higher than the shore. Sometimes when 

 this condition exists an unusual flood loosens the peat and 

 pours it in a devastating torrent of mud over the neigh- 

 boring land. 



Peat can be formed only in the presence of excess of 

 moisture. Otherwise the decay is complete instead of par- 

 tial. Cold assists in the prevention of complete oxidation; 

 hence we find peat more abundant in high latitudes than 

 low. There is present in such accumulations small quan- 

 tities of humic acid and hydrocarbons similar to bitumen. 

 These act as preservatives not only to the vegetable matter 

 but animal as well that may be present. Bodies have 

 been preserved for centuries in such swamps. In 1747 

 there was found in an English bog the body of a woman 

 with skin, hair and nails nearly perfect and with sandals 

 on her feet. In Ireland was found the b^dy of a man 

 dressed in coarse hair cloth eleven feet beneath the sur- 

 face. A number of other bodies in similar conditions have 

 been discovered and countless skeletons have been dug up 

 in bogs. 



It is interesting to study the growth of peat. Given a 

 pond or lake with a growth of sphagnum and shrubs on 

 the shore and the conditions are right. The vegetation 

 slowly works its way outward over the surface of the wa- 



