Gilgai in the Quaternary

Hallsworth, E. G.; Beckmann, G. G.

doi:10.1097/00010694-196906000-00005

Cited by 39 publications

(8 citation statements)

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“…Calcretes are present (rarely) from the Precambrian to the Ordovician (e.g. Post & Long, 2008) and vertic palaeosols should not be dependent on vegetation provided that enough smectite‐rich clay is available for their formation (Hallsworth & Beckman, 1969; Love & Williams, 2000). The field localities from VS 4 to VS 6 represent subtropical to mid‐latitudes, which may partially account for the increased prevalence of these features.…”

Section: Introductionmentioning

confidence: 99%

Alluvial facies evolution during the Palaeozoic greening of the continents: case studies, conceptual models and modern analogues

Davies¹,

Gibling²,

Rygel

2011

Sedimentology

108

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The Palaeozoic greening of the continents -the appearance and expansion of embryophytes (land plants) in terrestrial environments -was arguably the most fundamental Phanerozoic change to the Earth system. Thirteen case studies of Cambrian to Devonian fluvial deposits from North America and Europe are documented here to illustrate the evolution of fluvial style during this period. During the Cambro-Ordovician, prior to the advent of terrestrial vegetation, fluvial systems laid down relatively coarse sands with little mud, resulting in self-formed channels and an architecture dominated by broad sheets of trough cross-beds (sheet-braided style). Similar deposits formed across a wide range of latitudes, and passed basinward into sandy coastal deposits. From the mid Ordovician onwards, an increase in floodplain mudstone corresponds broadly with the appearance of embryophytes, which would have progressively enhanced upland weathering, mud production and floodplain storage of fines. During the Late Silurian, small heterolithic channel bodies with lateral-accretion sets provide the first evidence of meandering channels, and floodplain mudstones contain more varied palaeosols, especially calcretes which appear abundantly for the first time. By the Early Devonian, channel deposits comprise sandstone lenses (channelled-braided style), probably due to the increased bank strength and cohesion and reduced potential for sediment sorting imparted by sand-mud mixtures. Muddy coastal deposits are prominent. By the Upper Devonian, fluvial deposits commonly contain fossil trees and large mainstem meandering channels with lateralaccretion sets, indicating that rooted vegetation stabilized channels. The advent of stable floodplains with levées, crevasse splays and organic litter would have encouraged the diversification of terrestrial invertebrates, which left alluvial ichnological signatures from the Late Silurian onwards.

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Section: Introductionmentioning

confidence: 99%

Alluvial facies evolution during the Palaeozoic greening of the continents: case studies, conceptual models and modern analogues

Davies¹,

Gibling²,

Rygel

2011

Sedimentology

108

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“…Pseudoanticlines also occur at Some levels within the floodplain deposits. The Wessex Formation structures are comparable with modern gilgai, which are believed to be formed by superficial compression due to seasonal clay swelling and drying in warm dry regons in clay-rich alluvial soils (Hallsworth & Beckmann. 1969;Allen, 1973Allen, , 1986.…”

Section: Pulueoclimutementioning

confidence: 77%

The palaeoecology of the dinosaurs of the Wessex Formation (Wealden Group, Early Cretaceous), Isle of Wight, Southern England

Insole

Hutt

1994

Zoological Journal of the Linnean Society

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The Wessex Formation on the Isle of Wight yields an Early Cretaceous dinosaur fauna. Sedimentological evidence shows that this represents a mosaic of fluvial, floodplain and lacustrine environments within a relatively narrow east‐west oriented valley. The vegetational cover on the alluvial plain had a savannah‐or chaparral‐like aspect, probably of low productivity. The relative scarcity of small aquatic vertebrates, absence of coals, abundance of oxidixed sediments and the presence of immature calcretes indicate seasonal water supply. The dinosaur taxa compising the Wessex Formation faunal assemblage represent a single palaeocommunity which inhabited the local alluvial plain, although some species may have been transient. The fauna had a relatively low diversity and this is attributed to the low productivity of the local vegetation. Iguanodontids and Hypsilophodon were the dominant elements in the fauna. In contrast to Late Jurassic dinosaur faunas, sauropods are less abundant in the Wessex Formation, although they remain taxonomically diverse. It is concluded that climatic changes which took place in the Late Jurassic or Early Cretaceous resulted in the appearance of low productivity vegetation and that this was incapable of supporting large sauropod populations.

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“…The calcretes at Bonar Head show pedogenic features, and calcareous cements and fissure fills in underlying strata precipitated from groundwaters. The associated red mudstones are vertic palaeosols, and their prominent, concave up joint systems resemble the mukkara structure formed in modern soils under conditions of seasonal, deep soil wetting (Hallsworth & Beckman, 1969;Knight, 1980). Similar calcareous and vertic palaeosols are present locally in Carboniferous rocks across Euramerica (Schutter & Heckel, 1985;Besly, 1988).…”

Section: Discussionmentioning

confidence: 89%

Palaeovalleys and protozoan assemblages in a Late Carboniferous cyclothem, Sydney Basin, Nova Scotia

Gibling

Wightman

1994

Sedimentology

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The early Stephanian Bonar Cyclothem of the Sydney Basin, Nova Scotia, contains an erosional surface cut through coastal plain strata with economic coals and distributary channel bodies. The erosion surface is interpreted as a palaeovalley 20 m deep and at least 7 km wide that marks a sequence boundary formed during relative fall in sea level. The palaeovalley is filled with stacked alluvial channel bodies which become more isolated as the valley fill passes upward into red, alluvial plain deposits, probably laid down in an anastomosed river system. In an adjacent, interfluve area, calcretes and red, vertic palaeosols cap coastal strata. Assemblage analysis of agglutinated foraminifera and thecamoebians indicates that the palaeovalley was filled with freshwater sediments before an initial marine transgression flooded the alluvial surface and adjacent interfluve. Valley incision probably reflects glacioeustatic sea level fall. However, the alluvial nature of the valley deposits suggests that valley filling reflects an abundant sediment supply during lowstand and/or transgressive stages and was not a direct consequence of sea level rise. During the subsequent transgression phase, aggradation was rapid as sediment supply apparently kept pace with rising sea level. Features of both channel and extra‐channel facies suggest that seasonality intensified during the transition from coastal plain to palaeovalley and alluvial plain deposition.

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Gilgai in the Quaternary

Cited by 39 publications

References 0 publications

Alluvial facies evolution during the Palaeozoic greening of the continents: case studies, conceptual models and modern analogues

Alluvial facies evolution during the Palaeozoic greening of the continents: case studies, conceptual models and modern analogues

The palaeoecology of the dinosaurs of the Wessex Formation (Wealden Group, Early Cretaceous), Isle of Wight, Southern England

Palaeovalleys and protozoan assemblages in a Late Carboniferous cyclothem, Sydney Basin, Nova Scotia

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