THE PEAT CLISTASE. 



387 



in the pine. In the Hypnum peat the pine diminished still more, and the 

 open water had now become a moor with willows and birches. Sphagnum had 

 then appeared, the swamp-plants vanished, as also the pine, while the oak 

 and spruce became abundant. The uppermost part of the second layer 

 indicates that a forest of oaks, with some spruces and a few pines, and a shrub 

 layer of hazel and birch, developed in the Sphagnum moor. The pine then 

 vanished completely and the beech began to appear, first with the oak, and 

 then it became dominant. The spruce and yew maintained themselves with 

 the beech, and finally the pine again appeared, after which the record was 

 closed by a layer of mud. 



Weber (1896) has also given a profile of a fossil-bearing diluvial stratum, in 

 which he regards the peat-bed and the tufa as interglacial, the boulder sand 

 representing two glacial periods. 



Weber (1897) has found the following plants in sections of a moor at Bremen: 

 At a depth of 0.5 to 3.4 m. the section showed alder in particular, abundant 

 oak and birch in places, little pine, and isolated spruce, together with much 

 pollen of Tilia, Corylus, etc. The clay-bed beneath the moor contained 

 Sparganium ramosum, traces of Sphagnum, conifers, oaks, a probable Salvia, 

 and scattered grass seeds; above it lay sand and morainal material. The 

 section again showed moor at 92.8 to 94.6 m. but with no trace of plant 

 remains. Moor recurred at 98.7 to 99.1 m. in the section, and yielded remains 

 of Pinus silvestris, Betula, Alnv^ glutinosa, Carex, Sdrpus, Rubus, etc. This 

 was followed by clay and sand, and at 105.4 m. by Miocene clay. From this 

 it seems that this moor must have been formed not later than the first inter- 

 glacial period. 



Weber (1898) has found that the great majority of moors in northwestern 

 Germany are high moors with the following structure : 



(1) Swamp peat of reeds or sedges; (2) forest peat; (3) older moss peat; 

 (4) horizon peat; (5) later moss peat. The horizon peat is assiuned to indicate 

 a long interruption of peat formation during which the high moor was covered 

 with Eriophorum and Calluna and sometimes with forest. The author con- 

 cludes from the sequence of the layers that northwestern Germany has had 

 since the glacial period two warmer dry periods and two cooler moist periods, 

 a conclusion more or less in harmony with Blytt's theory. At the present 

 time the peat vegetation is found only in the center of the great moors, for all 

 the other moorland is covered with uniform heath. This development is 

 explained as a consequence of the influence of man, especially in drainage. 



Hulth (1899) has studied the calcareous tufa deposits of west Gotland: 

 These deposits are now covered with a vegetation of birch, spruce, pine, etc. 

 Beneath this is found a layer (a) of tufa of 15 cm., with a humus margin (&) of 

 5 to 20 cm. This is followed by a tufa layer with meadow-chalk (c) 2.5 m. 

 thick, and this by a third layer of 10 to 25 cm., marked above and below by a 

 5 to 10 cm. layer of humus (d). The fourth layer consists of meadow-chalk 

 25 cm. to 1 m. thick (e), followed by a 10 cm. layer of tufa (/) on the bottom 

 layer of moraine sand {g). The tufa deposits in which a definite sequence 

 can be determined show many analogies to the sequence in the south Swedish 

 pea,t-moors. The black humus margins are regarded by the author as indi- 

 cating an interruption in the deposition of tufa, and are thought to correspond 

 with the pine-stump layers in the peat-moors. The lowermost tufa deposit 

 (/) contains Salix glauca, S. lanata, and S. reticulata, and is assigned to the 

 arctic period. Layer (e) lacks fossils, but its stratigraphic relations make it 



