Sadler effect
   HOME

TheInfoList



OR:

The Sadler effect describes variation in apparent sediment accumulation rates and
bed A bed is an item of furniture that is used as a place to sleep, rest, and relax. Most modern beds consist of a soft, cushioned mattress on a bed frame. The mattress rests either on a solid base, often wood slats, or a sprung base. Many beds ...
thicknesses back through time inherent to the
geological Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other E ...
sedimentary record.Sadler, Peter M. "Sediment accumulation rates and the completeness of stratigraphic sections." The Journal of Geology (1981): 569–584. Peter Sadler analysed what structure you would expect in a stratigraphic section under the hypothesis that bigger geological events – episodes of deposition, erosion, and the gaps between those events – are rarer. He showed that under these conditions it is inevitable that, on average, thinner stratigraphic sections, which cover shorter amounts of time, record faster accumulation rates than thicker sections, which record longer amounts of time.Schumer, Rina, Douglas Jerolmack, and Brandon McElroy. "The stratigraphic filter and bias in measurement of geologic rates." Geophysical Research Letters 38.11 (2011): L11405.Schumer, Rina, and Douglas J. Jerolmack. "Real and apparent changes in sediment deposition rates through time." Journal of Geophysical Research: Earth Surface (2003–2012) 114.F3 (2009). The effect equivalently states that more ancient packages of sediment in the stratigraphic record will record slower sedimentation rates stretched over longer periods of time. For instance, it explains the fact that in general, the more ancient geological periods of the Phanerozoic are longer than the more recent ones; i.e., the periods of the Palaeozoic are much longer than those in the Cenozoic. Conversely, it also explains that the maximum sediment accumulation rates seen in the Cambrian at the start of the Phanerozoic are almost two orders of magnitude lower than those observed in the Quaternary, at its end. The Sadler effect provides a powerful framework for understanding how information extracted from any given stratigraphic section differs from what should be expected under constant conditions – that is, it provides a
null hypothesis In scientific research, the null hypothesis (often denoted ''H''0) is the claim that no difference or relationship exists between two sets of data or variables being analyzed. The null hypothesis is that any experimentally observed difference is d ...
for analysing stratigraphy. It also provides techniques to estimate the completeness of a given stratigraphic section on a given timescale. Sections are less complete at shorter timescales, which means that at sufficiently short timescales and for some purposes, some sedimentary successions may contain essentially no useful information. For example, the Sadler effect has since been used to investigate whether apparent increases in global sedimentation rates across the last 5 Ma are real; how we might read the record of sediments deposited on
continental margin A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margi ...
s;Jerolmack, Douglas J., and Peter Sadler. "Transience and persistence in the depositional record of continental margins." Journal of Geophysical Research: Earth Surface (2003–2012) 112.F3 (2007). to interpret fluvial processes such as river avulsion; and to understand what information, and which processes at what timescales, can be preserved in sediments.Jerolmack, Douglas J., and Chris Paola. "Shredding of environmental signals by sediment transport." Geophysical Research Letters 37.19 (2010).


See also

* Sedimentology *
Sequence stratigraphy Sequence stratigraphy is a branch of geology, specifically a branch of stratigraphy, that attempts to discern and understand historic geology through time by subdividing and linking sedimentary deposits into unconformity bounded units on a variety ...
*
Tectonic–climatic interaction Tectonic–climatic interaction is the interrelationship between tectonic processes and the climate system. The tectonic processes in question include orogenesis, volcanism, and erosion, while relevant climatic processes include atmospheric circula ...


References

{{Geologic Principles, state=collapsed Sedimentology Earth sciences Physical geography