Chapter 2 Flashcards
Formation of soil
Pedogenesis
A three-dimensional soil body used as the base of reference.
Smallest unit of soil body.
Pedon
Formed of cooled magma.
Makes up bedrock foundation of continents.
Includes:
-granite
-rhyolite
-gabbro
-basalt
Igneous rock
Made of loose layers of sediment that was weathered on ancient sea floors.
Includes:
-sandstone
-shale
-limestone
Sedimentary rock
Rock altered by heat and pressure
Metamorphic rock
Metamorphosed granite
Banded appearance
Gneiss
Metamorphosed sandstone
Most resistant widespread rock
Metamorphosed via silica solution
Quartzite
Metamorphosed shale
Slate
Metamorphosed limestone
Marble
Organisms that decompose dead organic matter
Saprophytes
Weathered (decomposed) loose rock
Saprolite
Unconsolidated material above solid bedrock
Regolith
Composed of an alga and fungus
Decomposes rock
Litchen
Chemical reactions that alter the molecular composition of minerals
Chemical weathering
Hydrogen ions (H+) in water replace metallic ions in minerals
Hydrolysis
Building block of clay
Silicic acid
Loss of electrons
Ex. Rusting
Oxidation
Expansion of a mineral due to attached water molecules
Often occurs after oxidation
Hydration
Gain of electrons
Reduction
5 factors of soil formation
Parent material, climate, living organisms, topography, time
Weathered rock slowly broken up on site or transported by nature
Parent material
Sand found in arid and subhumid climates
Originally deposited by water
Often shifted into dunes by wind
Eolian sand
Wind-formed deposit made of mostly silt
From floodplains of glacial rivers
Loess
Unsorted mix (till) of stones/sand/silt/clay left behind by glaciers
Glacial deposits
Ridge formed by till deposited at the edge of glaciers
Moraine
Sand/gravel left behind from glacial melt waters
Outwash
Sediment deposited by rivers/streams in valleys
Alluvium
Gravity-transported deposit found at the base of foothills and mountains
Colluvium
Chunks of broken rock at the foot of a mountain
Talus
Description of a land’s surface features
A graded layout of the land
How hilly or level a land is
Topography
Cross section of soil horizons
Soil profile
Horizon layer of plant residue
O horizon
Horizon of topsoil
A horizon
Eluvial or leech layer horizon
E horizon
Horizon of subsoil
B horizon
Horizon of unconsolidated material under B horizon
C horizon
Horizon made of bedrock found within a few feet from soil surface
R horizon
Upper portion of soil profile that is altered by soil-forming factors
(Horizons A, E, and B)
Solum
