A BOTANICAL SURVEY OF THE HURON RIVER VALLEY 1 



VII. POSITION OF THE GREATEST PEAT DEPOSIT 



IN LOCAL BOGS 



George Plumer Burns 



(with FIVE figures) 



The general appearance of the vegetation of the peat bogs in the 

 Huron River valley has been fully described by Transeau (8) and it is 

 not necessary to give a detailed account in this paper. The plants are 

 usually growing in a more or less regular zonal arrangement somewhat 

 as follows: (i) open water with submerged plants, (2) water lilies, 

 (3) floating sedge, (4) bog shrubs, (5) tamaracks, (6) maple-poplar, 



(7) willow or marginal zone. 



There is wide variation in the position of the greatest amount 

 of peat deposit and the width of the various zones. Even a casual 

 survey of a number of local bogs emphasizes the fact that the open 

 water is seldom in the center of the original post-glacial lake. The 

 zonal arrangement is usually broken on one side, some zones being 

 entirely lacking. In fact it is not uncommon to have all peat deposit 

 lacking at certain places along the shore. According to some writers 

 (7) the greatest accumulation of peat is found on the western side, 

 in regions with prevailing westerly winds. In large basins which are 

 only partly filled it is common to find open water occurring toward 

 the eastern side. The wave-action produced by the westerly wind is 

 supposed to hinder bog plants from obtaining a foothold on the east- 

 ern shore. The shoreward push of the ice is also a factor of impor- 



tance in this connection (8, p. 418). 



A study of the bogs near Ann Arbor soon revealed the fact that the 

 greatest accumulation of peat on the western side was by no means 

 common to all bogs. In fact the greatest variation was found within 

 very short distances. At Dead Lake it is on the southern side (1); 

 at Mud Lake, about one-half mile (8oo m ) west, it is on the northern 

 side (6) ; at First Sister Lake, it is on the western side (9) ; at a small 

 bog near Carpenter's Corner it is toward the east (7). 



1 Contribution 112 from the Botanical Laboratory of the University of Michigan. 



4451 



[Botanical Gazette, vol. 47 



