Perturbation (from
Latin: ''perturbare'' "to confuse, disorder, disturb", from ''per''- "through" + ''turbare'' "disturb, confuse," from ''turba'' "turmoil, crowd") is a set of
pedology (soil study) and
sedimentary geology processes relating to changes in the nature of water-borne
alluvial sediments and ''in situ'' soil deposits over time.
* Pedoturbation (from Greek: πέδον (''pédon''), "soil") involves mixing between soil horizons, and is an important factor in soil formation. Pedoturbation includes
churning clays,
cryoturbation, and bioturbation. Types of
bioturbation
Bioturbation is defined as the reworking of soils and sediments by animals or plants. It includes burrowing, ingestion, and defecation of sediment grains. Bioturbating activities have a profound effect on the environment and are thought to be a pr ...
include faunal pedoturbation (animal
burrow
An Eastern chipmunk at the entrance of its burrow
A burrow is a hole or tunnel excavated into the ground by an animal to construct a space suitable for habitation or temporary refuge, or as a byproduct of locomotion. Burrows provide a form of sh ...
ing), and floral pedoturbation (root growth,
tree-uprootings). Pedoturbation transforms soils through destratification, mixing, and
sorting
Sorting refers to ordering data in an increasing or decreasing manner according to some linear relationship among the data items.
# ordering: arranging items in a sequence ordered by some criterion;
# categorizing: grouping items with similar pro ...
, as well as creating preferential flow paths for
soil gas and
infiltrating water. The zone of active bioturbation is termed the
soil biomantle.
* Soil perturbation that is not pedoturbation.
Precipitation of surface salts also causes localized disruption of soils. Because it does not result in mixing between soil horizons, it is not considered pedoturbation.
* In geology,
bioturbation
Bioturbation is defined as the reworking of soils and sediments by animals or plants. It includes burrowing, ingestion, and defecation of sediment grains. Bioturbating activities have a profound effect on the environment and are thought to be a pr ...
is the displacement and mixing of
sediment particles (i.e. sediment reworking) and solutes (i.e. biologically-mediated
irrigation) by
benthic zone
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning " ...
(bottom water)
fauna (animals) or
flora (plants). Activity of
bacteria is yet another important cause of perturbation in the
geological record.
Field termites are especially important in
tropical climate regions within 15° of the equator.
Lofjle e Kubiniok, ''Landform development and bioturbation on the Khorat plateau, Northeast Thailand'', Nat.Hist.Bull.Siam Soc. (56), 1996
See also
* Turbidite
References
{{reflist
Sedimentology