[1905 TRANSEAUBOGS OF THE HURON RIVER VALLEY 367 



land through reef building. These swamps have been described by 

 SHALER, KEARNEY, JULIEN, and others (46, 26, 24, 7). They reach 

 their greatest development in eastern Virginia, North Carolina, 

 Florida, and the Mississippi floodplain. They may contain either 

 salt or fresh water, and their vegetation is noted for its density and 

 luxuriance. 



The geographical distribution of peat deposits is of interest in 

 this connection because it points to certain factors which contribute 

 to the preservation of humus materials. Certainly in arctic latitudes 

 the most significant factor is the low temperature, for humus accu- 

 mulates to great thickness even with a scant vegetation. In the 

 northern states and southern provinces of Canada, peat is associ- 

 ated with basins containing stagnant water or cold springs. The 

 annual increment from the vegetation is greatly increased over that 

 of the tundra. Mild temperatures and stagnant waters combine 

 to preserve the plant debris. When we come to the coastal plain 

 swamps of the southern states, this process takes place only where a 

 luxuriant vegetation is combined with areas of stagnant water of 

 considerable depth. 



To put it sharply, we may say that, in spite of the scant vegetation, 

 the cold of the tundra results in peat accumulation. In temperate 

 latitudes, mild temperatures and stagnant water combine to prevent 

 the complete disintegration of a vigorous vegetation. In the south, 

 in spite of the high temperature, the luxuriance of the vegetation 

 and stagnant water unite to make peat formation possible. 



THE PROCESSES INVOLVED IN PEAT FORMATION. 



When for any reason the living protoplasm in a plant or any of 

 its organs is brought to the condition of death rigor, the continuance 

 of this state for a prolonged period inaugurates certain chemical 

 and physical processes which result in the breaking down of the 

 exceedingly complex structures and compounds making up the living 

 plasma. Among the first outward signs of such disorganization 

 is the loss of water. The cells of soft tissues lose their normal form, 

 and in any case the tissue becomes more or less filled with gases. 

 The protoplasts as such disappear, and in their place granular 

 carbohydrate and proteid bodies are to be found. 



