Lec 3B rev Soil Formation and Parent materials 3 2 2013 Soil Formation Soil Formation Parent Materials Soil is the upper portion of the earth s crust Soil is the more physically chemically and biologically altered portion of the earth s crust Soil is the zone of interaction between the underlying rock material and the earth s atmosphere and biosphere Parent Materials Soil is a natural body it is the result of the interactions among climate and organisms as modified by relief topography acting on the parent material over long periods of time Soil f C O R P T Soil Formation CLASSIFICATION OF PARENT MATERIALS Parent Material Parent material young soil immature soil mature soil old soil Parent material is a passive soil formation factor It is the material that is altered by the actions of the other soil formation factors as soils form Parent material is very predictive of soil outcomes especially soil texture Residuum Material that formed from rock weathered in place No transporting agent was involved Older soils are often developed from residuum Transported Material that has been transported by some agent The material is often sorted to some degree Energy lending processes include Gravity Moving water Glaciers Wind 1 Lec 3B rev Soil Formation and Parent materials 3 2 2013 Lacustrine Material that is moved by water and deposited in fresh water lakes Coarser particles are close to the shore fine particles dominate toward center of the lake or layered fine coarse clays silts varves Rivers and Streams Alluvium Material deposited on flood plains of active streams Usually stratified as different flood episodes deposit different sized materials at a given site Soil Pit Flood Plain Active Stream Alluvial Landforms Alluvial Fans These materials are often deposited in fan shaped deposits in high energy environments at base of slopes Deltas Sediment carried by streams deposited in slower water Floodplains Area above rivers and below terraces the bottom of a river at flood stage Terraces Old abandoned floodplains 2 Lec 3B rev Soil Formation and Parent materials 3 2 2013 Floodplain Soil Formed in Alluvium Gravity Colluvium Material moved by gravity and deposited at the base of steep slopes Usually very coarse textured The talus slopes of the southwestern U S A are examples Big rocks tend to roll furthest down slope Buried A horizons Colluvium Steep Slopes Soil Pit Poorly Developed Soils Erosion Deposition Hazard Generally Coarse Texture depending on slope Colluvium in Action Wind Eolian Sandy material deposited by wind Loess Silty material deposited by wind very important in Illinois Dune sand Found at coastal beaches and present in Illinois Volcanic ash important in western US must be near volcano 3 Lec 3B rev Soil Formation and Parent materials 3 2 2013 Wind Loess Silt sized material deposited by wind Source of loess was barren flood plains left after major rivers swollen with glacial meltwaters receded Illinois Also blows off of deserts China If the climate is right makes very good agricultural soils best in the world for growing corn and soybeans Illinois Muscatune silt loam and Iowa Muscatine silty clay loam Wind Eolian sand Wind deposited sand sized material Often from the same origin as loess but not transported as far from the source Moves by saltation i e bouncing In Illinois Mason Tazewell Whiteside Lee Kankakee counties and others Loess thickness in Illinois Loess thickness in central U S 4 Lec 3B rev Soil Formation and Parent materials 3 2 2013 Loess and Dune Sand Around The World Best P M for agriculture Reason Illinois soils are so productive Wind Volcanic Ash Pumice Cinders Ash Volcanic ejecta Volcanic Soils Formed in Volcanic Ash Generally Fertile Well Drained Marine Material deposited by streams into marine environments Coastal Plain Sediments Tends to be the finer material that has been transported long distances Often is influenced by the salinity of the marine environment 5 Lec 3B rev Soil Formation and Parent materials 3 2 2013 Organic Deposits Material deposited by plants dying into water Extensive agricultural use in MI MN and NC Surface soils predominately organic matter Wet naturally need to be drained for agriculture Subject to fire and subsidence Glaciers Illinois Glacial Max Glacial drift Material deposited by continental ice sheets includes Till and Outwash Till Glacial till is a mixture of rock material that has been ground into an assortment of different sized particles and moved by the action of glacial ice Deposited in ground lateral and terminal moraines Outwash Alluvial material that was deposited by streams of glacial meltwaters Coarse textured generally Landscape at Glacial Maximum Landscape after Glacial Retreat U of IL 28 000 B P 6 Lec 3B rev Soil Formation and Parent materials 3 2 2013 Wisconsinan moraines in Illinois 75 000 10 000 YBP U of IL Illinoisan Till Plain 180 000 125 000 YBP Glaciers Glacial Till Outwash Landforms Kames conical hill sorted by water often by filling cavities in a glacial ice sheet with sediment Appear as isolated mounds Source of gravel Eskers serpentine ridge meltwater flowing within beneath glaciers and carrying sediment When the ice melts these longitudinal deposits are revealed Usually coarse textured mined for gravel Kettles closed depressions left as ice blocks in outwash or till melt Outwash Plain Broad expanse of outwash often downslope of a moraine Associated Landforms Kame Moraine Pile of till at edge of moraine terminal recessional or lateral Till Plain or Ground Moraine Level plain of till from beneath the glacier To see one look around you The campus is built on an extensive till plain Drumlin Pile of till in a large cigar shaped hill oriented with the direction of ice movement Glacial Landforms Northern 75 of Illinois 7 Lec 3B rev Soil Formation and Parent materials Waning Stages of Wisconsinan Glaciation 3 2 2013 Soils of Illinois Parent Materials Most common 1 Loess 63 2 Till 12 Note Glacial Advance 11 800 ybp 3 4 5 6 1 Wisconsinan 2 Illinoisan Alluvium 10 Outwash 8 Residuum 5 Lacustrine 2 8