Fragipan formation in argillic brown earths (Fragiudalfs) of the Milfield Plain, north‐east England. I. Evidence for a periglacial stage of development

Abstract

SUMMARY In this first of three papers, the parent materials, morphology and field relationships of soils with fragipans, similar to those in north‐eastern United States, are described and analyses of their chemical and physical properties are presented to support a periglacial stage of development. The soil materials have been affected by periglacial processes, including ice‐wedge formation, the age of which has been established by reference to a buried paleosol. The fine earth bulk density of the fragipans is between 1.75 and 1.91 g cm−3 whereas the density of overlying Eb horizons is < 1.40 g cm−3. The formation of the compact lenticular structures and polygonal fissuring of fragipans is ascribed to the former presence of permafrost during the Loch Lomond Stadia1 11 000 to 10 000 years B.P. The polygonal fissures, after subsequent infilling with illuvial material, have determined the position of the greyish polygonal zones which have formed by the eluviation of Fe and Mn from fissure infill and fissure walls by redox processes. Clay migration from the Eb horizon into the fragipan is well marked. Clay and silt have also been locally removed from the upper parts of the greyish zones and redeposited towards their lower parts. Similar textural degradation has affected eluvial pockets in the upper fragipan. It is concluded that periglacial processes fully explain the genesis of macrostructural features but not the distinctive consistence of the fragipan.

Geoarchaeology of the Milfield Basin, northern England; towards an integrated archaeological prospection, research and management framework

“…These deposits are developed most extensively in western and northern parts of the basin, where they comprise glaciodeltaic and glaciofluvial sand and gravel terraces (Category 1a) that locally feature closed depressions, palaeochannels and inset fluvial terraces (Category 1b). This suite of landforms reflects the development and local fluvial reworking of an outwash delta prograding from the Glen valley into a former ice-dammed lake ('Lake Ewart'; Clapperton, 1971;Payton, 1980Payton, , 1992. Broad palaeochannel belts extending between Lanton and Milfield, on the western fringe of the study area, and between Coupland and Galewood to the south of the airfield (Figures 3 and 4) are interpreted by Payton (1980Payton ( , 1992 as lateglacial courses of the River Glen.…”

“…This suite of landforms reflects the development and local fluvial reworking of an outwash delta prograding from the Glen valley into a former ice-dammed lake ('Lake Ewart'; Clapperton, 1971;Payton, 1980Payton, , 1992. Broad palaeochannel belts extending between Lanton and Milfield, on the western fringe of the study area, and between Coupland and Galewood to the south of the airfield (Figures 3 and 4) are interpreted by Payton (1980Payton ( , 1992 as lateglacial courses of the River Glen. Glaciofluvial sand and gravel deposits of Category 1a also locally mantle the lower valley slopes on the southern and eastern flanks of the basin (Figures 2-4).…”

“…Solid and drift geology of the Milfield basin (redrawn after Payton, 1980Payton, , 1992 showing study area (inset frame).…”

Cemented Horizons and Hardpans in the Coastal Tablelands of Northeastern Brazil

“…Opposing some studies about fragipans developed under periglacial conditions (Payton, 1992(Payton, , 1993Weisenborn and Schaetzl, 2005), the values of Fe, Al, and Si obtained in this study from different extractions increased in the fragipan (p-PAC) in relation to the horizon overlying it. Some micromorphologial features are common to these soil profiles, such as the constant presence of coated and unfilled pores, ferri-argillans, and matrix with intense Fe diffusion resulting from redoximorphic conditions, which form the placic horizons.…”

“…The development of fragipans by the compression of particles has been explained by different theories, which are not mutually exclusive: past periglacial conditions (Bryant, 1989;Payton, 1992) and water-driven collapse deposits (Assallay et al, 1998), including the effect of earthquakes in the liquefaction of waterlogged deposits (Green et al, 2005). Several studies, along with Soil Taxonomy (Soil Survey Staff, 1999), report the relevance of low-crystallinity materials, such as Si, Fe, and Al compounds, regarding expression of two of the most singular properties of a fragic material: breakability under moist conditions, due to sudden rupture of aggregates under pressure (the air is vigorously expelled as the pores are saturated with water); and the soil aggregate slaking after a relatively short time period of water immersion (Norfleet and Karathanasis, 1996;Duncan and Franzmeier, 1999).…”