I NT ROD UC TION. 1 5 



water, which, held up by impermeable strata and remaining on the surface 

 for some time, thus protects the parts of plants which find their way into it 

 from rapid normal decay. Instead of this decay, a different chemical 

 change takes place with formation of hydrocarbons and acids rich in carbon 

 (humus-acids). By this means the vegetable mass, which to some extent 

 breaks up into diminutive fragments, becomes converted in comparatively 

 short periods of time into a tolerably homogeneous brown to brownish 

 black pulpy substance, the constituent elements of which can no longer be 

 perceived without minute examination. Two kinds of peat essentially 

 different from one another may be distinguished according to the mode of 

 formation, and especially also according to the plants which supplied 

 the material 1 . 



There is, first, the peat of meadow peat-mosses and lake-marshes (low- 

 land or lake-turbary), such as so often occupy the bottoms of valleys and 

 other depressions in the north of Germany, or are found everywhere accom- 

 panying the course of streams and covering a greater or less extent of ground. 

 Such peat-beds are in their first stage generally lakes bordered by marshy 

 ground, but the remains of vegetation gradually push forward from the edge 

 of the lake and ultimately form an unstable covering over the whole surface 

 of the water, and continually sinking to the bottom there collect and fill up 

 the lake, which thus passes into its second stage. The plants which form the 

 sinking mass of peat are mainly Cyperaceae, with some grasses and other 

 angiospermous growths and a few mosses. The mosses are not Sphagna 

 so much as Hypneae, Aulacomnion, Meesia, Philonotis, and similar forms. 

 The matter which covers the bottom of the lake is a brown detrital mass 

 mixed with many membranous shreds of roots, leaves and leaf-sheaths. 

 In peat-mosses of this kind, if the depth is not too great, Phragmites 

 vulgaris plays an important part. With them may be classed the swamps 

 of the coasts of North Germany, which through sinking of the land or the 

 irruption of the sea are now below the sea-level, and are overlaid by sand 

 and beds of clay. Here the decay of the component substances is less 

 perfect ; the leaves and stalks of reeds may be quite plainly distinguished 

 in the exfoliating peat. These products are much less valuable than the 

 good rich peat formed in meadow peat-mosses and deep lake-marshes. 



We have, secondly, the peat of peat-bogs (mountain turbary), which is 

 proper rather to mountain districts, but may develope in favourable circum- 

 stances upon the basis supplied by former peat-mosses. In northern countries, 

 and especially in the neighbourhood of both poles, peat-bogs are common at 

 lower levels ; in the lowlands of Germany they occur chiefly on the expanses 

 of higher ground which separate the river-valleys from one another. Of all 

 the German peat-bogs those in the district of Ems have been most carefully 



1 Senft (1). 



