CUMULOSE SOILS 43 



accumulated on the bottom of the depression. The 

 dead remains are kept saturated with water, which 

 excludes the air and keeps down the temperature, and 

 otherwise hinders decay, so that the annual additions 

 exceed the annual loss by decay. Hence, an accumu- 

 lation of vegetable remains is inevitable. This is the 

 genesis of hundreds of the mucky marshes throughout 

 the country. Old abandoned stream channels are a 

 common beginning of such accumulations. Very similar 

 in origin are muck and peat beds, which were formerly 

 deep lakes. A peculiarity of fresh water deposits of this 

 sort are beds of marl, or impure lime carbonate, beneath 

 the vegetable matter. 



A slightly different type of these deposits are the 

 seacoast swamps from Massachusetts to Texas, many of 

 which are of large extent. These have formed in brackish 

 water 



The chemical composition typical of many of the 

 cumulose deposits is shown in the accompanying table. 

 The physical and chemical properties of such soil will 

 be more fully discussed under the head of physical 

 properties of organic soils. 



Cumulose deposits are characterized chemically by 

 their large percentage of carbonaceous matter. If the 

 vegetation suffered no decay and received no mineral 

 matter, it would be simply a mass of plant tissue; but, 

 as has been stated, there is every degree of "wash" 

 mixed with the dead plants. These also have accumu- 

 lated to all depths from almost nothing to many feet in 

 thickness. Many areas of soil, such as Miami black clay 

 and the Clyde soils of the northern states, and the 



