L6: Lithosphere, Weathering, and Soil Formation Overview

Lithosphere

Solid outer layer of Earth, includes crust and upper mantle.

Mechanical Weathering

Physical breakdown of rocks without chemical change.

Chemical Weathering

Breakdown of rocks through chemical reactions.

Role of Organisms in Weathering

Biological activity contributes to soil formation and rock breakdown.

Formation of Soils

Process involving weathering, organic matter, and mineral accumulation.

Aluminosilicate Minerals

Primary minerals forming Earth's crust, containing aluminum and silicon.

Minerals

Natural compounds with specific chemical structures and properties.

Rock

Aggregate of one or more minerals, forming solid mass.

Granite

Igneous rock composed mainly of feldspar and quartz.

Igneous rock

Formed from cooling molten rock at various depths.

Oceanic crust

Denser, thinner crust primarily composed of basalt.

Continental crust

Thicker crust primarily composed of granite.

Alumino-silicate materials

Primary components of both oceanic and continental crust.

Basalt

Igneous rock, dense, forms oceanic crust.

Granite

Igneous rock, less dense, forms continental crust.

Plagioclase feldspar

Common mineral in igneous rocks.

Subduction

Oceanic crust sinks beneath continental crust.

Asthenosphere

Layer where melted subducting crust is added.

Accretion

Process of adding material to continents.

Metamorphosis

Alteration of rocks due to heat and pressure.

Spreading zones

Locations where new crust is created.

Rift zones

Continental areas where crust is formed.

Mechanical weathering

Physical breakdown of rocks by natural forces.

Chemical weathering

Alteration of rocks through chemical reactions.

Sedimentary rock

Formed from sediments settling in low-energy areas.

Sandstone

Sedimentary rock formed from sand particles.

Shale

Sedimentary rock formed from clay particles.

Chert

Sedimentary rock composed of microcrystalline quartz.

Metamorphic rocks

Rocks altered by pressure and temperature.

Gneiss

Metamorphic rock with banded texture.

Marble

Metamorphic rock formed from limestone.

Congruent dissolution

All components of a mineral dissolve completely.

Incongruent dissolution

Forms secondary minerals during the dissolution process.

Secondary minerals

Minerals formed from weathering processes.

Chemical weathering

Process releasing ions into water from minerals.

Evaporites

Sedimentary rocks formed from evaporated water.

Halite

Mineral formed from evaporated sodium chloride.

Calcite

Calcium carbonate mineral from evaporated water.

Gypsum

Calcium sulfate mineral from evaporated water.

Role of organisms

Catalysts for weathering and sedimentary rock formation.

Carbon dioxide in soils

Produced by respiring plants, animals, microbes.

Organic acids

Acids from plants that enhance mineral weathering.

Chelators

Substances preventing metal precipitation, aiding breakdown.

Biogenic minerals

Minerals formed by biological processes.

Hermatotypic corals

Corals that deposit calcium carbonate.

Coccolithophores

Algae that produce calcium carbonate shells.

Foraminifera

Amoeboid protists contributing to sedimentary rock.

Diatomaceous earth

Silica shells from diatoms, used in various applications.

Cation exchange capacity (CEC)

Soil's ability to retain and exchange cations.

Sesquioxides

Minerals like geothite and hematite in soils.

Clay minerals

Degraded aluminosilicates controlling soil chemistry.

Carbonate formation

Occurs when calcium concentration increases in soil.

Soil structure

Arrangement of soil particles affecting its properties.

Chemical characteristics of mineral soil

Influence retention and loss of substances in soil.

Evaporation

Process concentrating calcium, forming solid carbonate.

Calcium Carbonate

Solid formed from concentrated calcium during evaporation.

Arid Conditions

Dry environments where evaporation is common.

Phosphate Availability

Influenced by soil pH levels.

Neutral Soils

Optimal for phosphate availability.

Low pH

Causes PO43- to co-precipitate with Fe and Al.

High pH

Causes PO43- to co-precipitate with carbonate.

Phosphorus

Critical nutrient for plant growth.

Igneous Rock

Source of easily erodable phosphorus forms.

Fe and Al Sesquioxides

Traps phosphorus through weathering processes.

Soil Formation

Combination of mineral and biological particles.

Vertical Soil Structure

Result of water and plant interactions.

Soil Horizons

Distinct layers of soil with varying composition.

O Horizon

Organic matter layer at the soil surface.

A Horizon

Topsoil rich in organic material.

E Horizon

Heavily leached layer beneath topsoil.

B Horizon

Subsoil containing minerals from leaching above.

C Horizon

Parent material from which soil develops.

Sesquioxides

Iron and aluminum oxides formed in soils.

Chernozem

Soil type found in dry grasslands.

Spodosol

Soil type found in wet conifer forests.

Permafrost

Layer of permanently frozen soil.

Glacial Scouring

Soil removal process caused by glaciers.

Long Island Morraine

Landform created by glacial deposits.

Weathering Types

Includes mechanical and chemical processes.

Soil Profiles

Vertical cross-section showing soil layers.