Using a fluid bromide tracer, Dicke ( in Graf 1992 ) found molecular diffusion alone to penetrate soft sediments to 4 cm in one day and 8 cm after 4 days . Bioturbation can accelerate this process by up to a factor of ten.
42.
This is mainly due to the limited extent of burrowing activity; as such bioturbation became more prevalent throughout the Cambrian, environments capable of preserving organisms'soft parts became much rarer . ( The pre-Cambrian fossil record of animals is sparse and ambiguous .)
43.
The Adamantina Formation, which is Turonian to Santonian in age, was deposited in semi-arid conditions around 95 million years ago . " Morrinhosuchus " was found in an outcrop of reddish sandstone with carbonate nodules, concretions, and areas of intense bioturbation.
44.
The ichnogenus is found both in anaerobic, organic-rich sediments and in oxic layers, where it is almost invariably the last in the bioturbation sequence, i . e ., it was placed deep within the sediments, away from oxidizing surficial and interstitial water.
45.
Wilkinson, M . T ., P . J . Richards, and G . S . Humphreys . 2009 . Breaking ground : pedological, geological, and ecological implications of soil bioturbation Earth Science Reviews, v . 97 ( 1-4 ), pp . 257 272.
46.
A 2010 project in the Kasouga Estuary, on the south-eastern coast of South Africa, found that this species contributed significantly to bioturbation, leading to a decline in microphytobenthic algae which in turn caused a significant decrease in numbers of the gastropod " Nassarius kraussianus ".
47.
Bioturbation is evident in tuff beds throughout the member due to the disruption of sediments by Channeled debris flows interbedded with turbides make up the lower portion of the member and are overlain by fine sandstones ( followed by coarser sandstones and coquinas ) that make up the upper portion of the member.
48.
The increased level of bioturbation meant that sulfur, which is steadily supplied to the oceanic system from volcanoes and river runoff, was more readily oxidised-rather than being rapidly buried and sitting in its reduced form ( sulfide ), burrowing organisms continually exposed it to oxygen, allowing it to be oxidised to sulfate.
49.
Wilkinson and Humphreys offer evidence that bioturbation appears to be the most active pedogenic process operating in many soils . While probably close to the mark, research over multiple decades strongly indicates that bioturbation is the dominant process in the upper part of most soils, notable exceptions possibly being vertisols and cryosols, where shrink-swell and freeze-thaw processes, respectively, appear dominant.
50.
Wilkinson and Humphreys offer evidence that bioturbation appears to be the most active pedogenic process operating in many soils . While probably close to the mark, research over multiple decades strongly indicates that bioturbation is the dominant process in the upper part of most soils, notable exceptions possibly being vertisols and cryosols, where shrink-swell and freeze-thaw processes, respectively, appear dominant.
