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During the
Mesozoic the paleopedological record tends to be poor, probably because the absence of mountain-building and glaciation meant that most surface soils were very old and were constantly being weathered of what weatherable materials remained. Oxisols and
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Other methods for classifying soil fossils rely on geochemical analysis of the soil material, which allows the minerals in the soil to be identified. This is only useful where large amounts of the ancient soil are available, which is rarely the case.
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are the dominant groups, though a few more fertile soils have been found, such as the extensive andisols mentioned earlier from
Jurassic Siberia. Evidence for widespread deeply weathered soils in the
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entisols and inceptisols, and with the growth of land vegetation under a protective ozone layer several new soil orders emerged. The first,
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is that very few of the soils found are extinct types. Despite the difficulties of identification mentioned earlier, this makes
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emerged in the late
Devonian and early Carboniferous, and have a continuous, though not rich, fossil record in eras since then.
309:, most fossil soils can be classified into one of the twelve orders recognised by this system. This is usually done by means of
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fossils are confined to the few periods of extensive continental glaciation - the earliest being 900 million years ago in the
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533:(the study of fossil soils) potentially very useful to understanding the ecological relationships in past ecosystems.
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Gradational alteration down from a sharp lithological contact like that between land surface and soil horizons
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but are rare as fossils because most of their mass consists of organic materials that tend to decay quickly.
382:, deeply weathered tropical soils, have a rich fossil record from the Paleoproterozoic onwards. Outside of
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Drying out of hydrous ferric oxides to anhydrous oxides - again due to the presence of more available O
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Decomposition of organic matter that was once present in the old soil. This hinders the recognition of
386:, oxisols have generally been the dominant soil order in the paleopedological record. This is because
333:, soils were subject to much more rapid erosion and most fossils from this period are of undeveloped
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just before land vegetation began to emerge. Other major andisol fossils can be found in the middle
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Tubular structures that branch and thin irregularly downward or show the anatomy of fossilised
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are known only from the
Carboniferous and from a few periods since that time - though less
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from soils with very low concentrations of nitrogen, phosphorus, calcium and potassium.
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412:. Oxisols were not vegetated until the late Carboniferous, probably because microbial
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An important difference between the paleopedological record and the fossil record of
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onwards (though little is known about when they were first vegetated), whilst a few
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514:, as grasslands evolved. The most abundant paleopedological record is that of the
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soils of the present, are unique in their geological youth, being known from the
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was not before that point advanced enough to permit plants to obtain sufficient
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tend to be altered by various chemical and physical processes. These include:
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can be seen in abundant oxisols and ultisols in now-heavily glaciated
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content and also causes changes in circulation linked closely by
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as the former soil becomes dry and more oxygen enters the soil.
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546:(2nd edition), 2001, Blackwell Science; Malden, Massachusetts.
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The keys to recognising fossils of various soils include:
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with few soils different from types widely found today.
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soils otherwise similar to spodosols are known from the
204:, or preserved at geological unconformities, especially
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Soils of the past: An introduction to paleopedology,
193:. The paleopedological record consists chiefly of
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138:but its sources remain unclear because it lacks
423:Owing to their extreme climatic requirements,
48:introducing citations to additional sources
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442:The earliest land vegetation is found in
243:that was in the soil when it was present.
169:Learn how and when to remove this message
478:and may constitute an extinct suborder.
38:Relevant discussion may be found on the
301:Soil fossils are usually classified by
282:replacements like those of soil clods (
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349:have a continuous fossil record from
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246:Oxidation of iron from Fe to Fe by
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408:to the development of continental
321:Records of the various soil groups
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31:relies largely or entirely on a
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278:Complex patterns of cracks and
223:has covered the ancient soils.
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364:and more abundantly from the
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360:fossils are known from the
219:soils occur in areas where
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542:Retallack, Gregory John;
510:but common only from the
59:"Paleopedological record"
208:escarpments or sides of
124:This article includes a
260:in the dry environment.
227:Problems of recognition
183:paleopedological record
153:more precise citations.
185:is, essentially, the
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303:USDA soil taxonomy
126:list of references
450:, emerged in the
311:X-ray diffraction
221:volcanic activity
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33:single source
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560:Paleontology
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504:agricultural
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145:Please help
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396:atmospheric
339:inceptisols
331:ozone layer
327:Precambrian
325:During the
151:introducing
554:Categories
537:References
516:Quaternary
496:Antarctica
410:ice sheets
392:glaciation
366:Ordovician
354:continents
241:vegetation
197:buried by
70:newspapers
500:Mollisols
488:Paleocene
464:Spodosols
448:histosols
418:nutrients
414:evolution
347:aridisols
343:Vertisols
202:sediments
195:paleosols
159:June 2013
100:June 2013
40:talk page
565:Pedology
492:Scotland
484:orthents
476:Tertiary
472:Mesozoic
460:ultisols
456:Alfisols
452:Devonian
384:ice ages
370:Jurassic
335:entisols
215:. Other
527:animals
512:Miocene
425:gelisol
380:Oxisols
374:Siberia
358:andisol
280:mineral
213:valleys
206:plateau
147:improve
84:scholar
523:plants
508:Eocene
468:acidic
289:cutans
272:traces
217:fossil
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210:river
199:flood
191:soils
132:, or
91:JSTOR
77:books
525:and
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284:peds
270:root
181:The
63:news
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