14. Soil and Weathering Flashcards
4 points on biosphere
narrow zone of contact bw lithosphere, atmosphere, hydrosphere
also called ecosphere
totality of all ecosystems worldwide
zone of life
what is lithosphere
continents + the ocean floor = lithosphere
solid crust of earth
three layers of the Earth
Crust, mantle, Core (outer and inner)
what is crust and its two parts
solid outermost layer of the earth
SIAL - silica and aluminium (upper, continental ;ayer)
SIMA - silica and magnesium (ocean floor_
4 points on the mantle
- 2850 km wide
- rich in iron and magnesium (FeMa)
- bw dense superheated core and thin, outer crust
- mantle is molten rock which contains minerals and metals
4 points on the core
- starts 2900 km from surface of Earth
- outer core and inner core
- outer core is liquid while inner core is solid
- mainly made up of nickel and Iron - NI(I)
4 points on minerals
- inorganic substances that occur naturally on the Earth’s crust
- rarely occur in pure form, usually in the form of rocks or ores
- lithosphere minerals combine in different ways to form rocks
- they need to be extracted from rocks
(6)commonly occurring rock forming minerals
silica
feldspar
mica
calcite
dolomite
gypsum
what are rocks and their types
aggregate of minerals that form the crust
igneous, sedimentary, metamorphic
5 points on igneous rocks
- first rocks to be formed
- cooling and solidification of magma
- crystalline and compact
- do not occur in layers or strata
- come in two forms: extrusive and intrusive
intrusive igneous rocks
formed when lava seeps in cracks/cervices and cools to from a rock with large crystals
ex. Granite
extrusive igneous rocks
formed when lava emerges during a volcanic eruption and solidifies on contact with air to form small crystalline rocks
ex. basalt
8 points on sedimentary rocks
- found on or near the Earth’s surface
- formed by the accumulation and compaction of layers of small particles of rocks and organic materials which has hardened over millions of years
- slow process
- found in layers or strata and contain fossils
- stratified structure
- calcite, conglomerate, sandstone, chalk
- divided based on how they are formed
- mechanically formed, chemically formed, organically formed
what type of rock is limestone
calcareous
3 points on metamorphic rocks
- metamorphosis means transformation
- metamorphic rocks are formed when igneous and sedimentary rocks undergo transformation under tremendous heat and pressure
- hardest and most durable rocks
3 points on importance of rocks
- used to build houses, dams etc
- manufacturing of cement
- hold great variety of minerals that yield metals (iron, manganese, copper)
plate tectonics
constant movement of plates of crust in the mantle
Gradation
a gradual change caused by external forces
denudation/degradation
process in which rocks are removed from the earth’s surface, resulting in general lowering/leveling of the land
aggradation
accumulation of sediment in low lying areas leading to an increase in their elevation
weathering
breaking down or dissolving of rocks, minerals, on the Earth’s surface because of action of elements of weather
erosion
process by which rock particles are carried elsewhere by agents like wind, water, moving ice and waves
factors affecting weathering (6)
local climate
mineral composition
structure of rocks
vegetation cover
amount of exposed rock
human activities
types of weathering
physical weathering
chemical weathering
biological weathering
physical/mechanical weathering
- rocks are broken into smaller pieces without a change in their chemical nature
FACTORS
extreme temperature differences during day and night (granular disintegration) - desert region
frost action (temperate regions)
expansion and contraction (exfoliation)
chemical weathering/decompostion
chemical composition of rock changes as it breaks into smaller pieces
TYPES
Oxidation (moisture in air)
Carbonation (carbon reacts with rainwater to form carbonic acid) limestone, chalk, marble
Hydration (rocks absorb water and it weakens them) - feldspar, potash
Solution (minerals within rocks dissolve to form a solution which gets washed away)- Limestone and rock salt
biological weathering
weathering of rocks due to plants, animals, or human action
Plants (grow in cracks and widen them)
Animals (burrow small cracks and live there, weakens rock material)
Humans (mining, quarrying, construction cause large scale damage)
soil
consists of mineral particles, moisture, living organisms like bacteria and earthworms, and decayed organic matter
provided structural support to plants, supplies water and nutrients
soil profiles
vertical section of the soil which extends from the ground surface down to where it meets underlying rock
parts of the soil profile
Top soil (uppermost layer, humus makes it fertile)
Sub - Soil (finer particles of rock clay and silt)
Parent Material (weathered rocks)
Bedrock (solid layer of unweathered rocks- determines composition of material)
soil erosion
refers to the removal of layers of the topsoil by natural agents like running water and wind
types of soil erosion
sheet erosion
gully erosion
examples of Badlands formed by gully erosion
Chambal Valley of Madhya Pradesh
soil conservation
prevention of soil from erosion and loss of fertility is soil conservation
7 ways of soil conservation
Afforestation (plant more trees)
Crop Rotation (rotate nutrient supplying plant with nutrient depleting plant)
Contour ploughing (crops are planted with the natural tilt, following the contours of the land)
Controlling overgrazing (move your dayum cattle)
Terrace farming (vertical steps/terraces are cut into hill sides, breaks flow of water from flood)
Strip cropping/Multiple cropping (narrow strips of land, same nutrient supplying/depleting cycle)
Fallowing ( like crop rotation but rotate an idle land instead)
