What is peat?

An accumulation of unconsolidated partially decomposed plant material found in waterlogged habitats of fen, bog and swamp. Thus, a peat bog is an area of wet peaty substrate rich in organic debris but low in mineral nutrients, with a vegetation of sedges, mosses and ericaceous shrubs. A peat bog should have a minimum thickness of stratum of 30 cm (otherwise it is an Anmoor).

Peat bog types

The following main types of peat bogs are distinguished (see Figure 1 below):

1. Lowland moor / topogenous bogs (Niedermoor/Flachmoor): dependent mainly upon underground water, consideralbly independent of climate conditions, bog surface is nearly horizontal, with a relatively quick decomposition of plant material.
    
2. Raised bog / ombrogenous bog (Hochmoor): dependent mainly upon precipitation / rain (humid climate conditions), raised bog surface due to piled up Sphagnum moss, extremely poor of nutrients and oxygen, acid environment.
    
3. Transitional moor (Übergangsmoor): transition bog type between a lowland and a raised bog.
    
4. Hanging bog (Hangmoor): dependent maily upon soild (soligenous) and upon running ground or surface water.
    

Within the raised bog and at its border several phenomena/zones are distinguished:

• Lagg: wet zone at the edge of a raised bog, whre the moor water is mixing with minerogenic soil ground water.
   
• Marginal slope (Randgehänge): relatively dry site with trees (e.g. mountain pine, downly birch).
   
• Pothole (Hochmoorsee, Kolk): site at the top of the raised bog, where the ground water table is visible.
   
• Rüllen and Sclenken: rüllen are somall centrifugal drainage channels, whereas schlenken ae shallow water holes perpendiculat to the rüllen.
   

The following main types of peat bogs are distinguished: lowland bog, transitional bog, raised bog, hanging bog (see figure xy)

1 - Overview of peatbog types
 

1 - A mountain lake (Lai da Vons, 1991 m; Upper Rhine valley, Grisons, Switzerland) with an alluvial bog as an example of a palaeoecological archive.

Formation of bogs

The most part of peat bogs are alluvial bogs, i.e. they are built up of:

• inorganic sediments (limnic deposits; clay, silt, sand, gravel, cobbles)
• biogenic sediments (limnic, telmatic, terrestrial deposits)

Examples of biogenic sediments

• sedimentary (allochthonous deposits): Gyttja (nekron mud), calcareous gyttja (marl), clay gyttja, diatomite (Kieselgur)
   
• sedentary (autochthonous deposits): different peats (named after the principal peat-forming plants found in the sediment). There are distinguished limnic, telmatic and terrestrial peats.

Palaeoecological archives

As peat bogs store plant microfossils (pollen grains, spores and other microfossils) and macrofossils, they are excellent archives of palaeoecology (flora and vegetation history, climate history, environmental history).

4 - Getting a drill core of an alluvial bog with a russian peat probe.

5 - A core sample of peat 50 cm long.

6 - A lake site with hydrosere vegetation and the silted-up zone with the corresponding sedentary/sedimentary deposits, e.g. peat or gyttia.

figure below shows hypothetic par bog section. Try to analyse tis archive of peleoecology while putting the following processes to the corresponding layer of the stratigraphy.

West (1977), Bradley (1985), Burga & Perret (1998), Göttlich (ed. 1990)

29 August 2011
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