A daliegat is a round or oval depression in a peat or lowland-bog area, usually a few metres across, formed by subsidence or by leaching of peat material. The phenomenon has both geological and cultural-historical origins and is related to the daliebult (the mound form).
How does a daliegat form?
There are two main explanations for the formation of daliegaten:
- Geological — during or after the last ice age, groundwater flows, ice-lens formation or subsidence of peat created a small basin
- Cultural-historical — in the Middle Ages, pits were dug in bog areas to extract peat or sample the soil; these later overgrew but remained recognisable as depressions
The diameter is usually 2-10 metres, the depth ranges from a few decimetres to more than a metre. Beneath a daliegat there is often a layer of peat remains, organic material or even archaeological finds.
Occurrence
Daliegaten are found in:
- Drenthe (especially on the Drents Plateau in the Netherlands)
- Friesland and Groningen in old peat lands
- Vechtdal, Twente and the Achterhoek
- Comparable features in bogs of north Germany and parts of the British Isles
In nature reserves they remain visible; on farmland they have often disappeared through levelling.
Significance for construction
For building projects in peat or lowland-bog areas, daliegaten are relevant:
- Soil variation — the soil stratification under a daliegat can differ markedly from the surroundings
- Foundation advice — soft, organic subsoil can cause additional settlement
- Archaeological investigation — required by law when daliegaten are suspected on a building plot
- Drainage — daliegaten collect water locally and can cause damp problems
Difference from other peat features
- Daliebult — the opposite of a daliegat: a mound instead of a depression
- Pingo scar — a depression surrounded by a rim, formed by a collapsed ice hill
- Dewpond — a shallow pool, often man-made as a cattle watering hole
Related terms
- Daliebult
- Pingo scar
- Peat
- Soil investigation
- Foundation advice
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