Friday, July 6, 2012

Lecture Notes about Geosphere


Areas of earth sci
1.       Geology – study of the earth
Physical geology – earth’s interior, rock cycle, etc.
Historical geology – origin og the earth, evolution
2.   meteorology – about the atmosphere, weather and climate
ooceanography – study of the ocean and marine life
aastronomy – study of the universe
eenvironmental science – interaction between the biotic and its environment
system – interacting parts that form a complex whole
composed of :
*cycles
*powered by
-sun
-earth interior

Earth is divided into spheres
*geosphere – solid part of the earth
*atmosphere – blanket of air
*hydrosphere – liquid part
*biosphere – living organism

Minerals 0 basically consist of elements
naturally occurring inorganic solids with definite composition which gives them unique physical properties
rocks – aggregates of minerals
compound of minerals
Characteristics of minerals
inorganic – absence of carbon (organic: made of carbon
exception: graphite and diamond
naturally occurring
solid – composed of crystal structures
– organized internal arrangements
definite composition

properties of minerals
crystal structure – organized arrangement of the minerals
example: NaCl
cleavage – breakage due to weak bonding
fracture – no definite breakage
color – obvious feature of a mineral
streak – color of the mineral in powdered form
hardness – resistance to abrasion or scratching
determined by Mohs’ scale
Relative scale
Mineral
10
Diamond
9
Corunlum
8
Topaz
7
Quartz
6
Potassium
5
Apatite
4
flouride
3
Calcite
2
Gypsum
1
talc

luster – the quality of the light reflected at the surface of minerals

Mineral compositions of the earth’s crust
element
Approximate % by weight
O
46.6
Si
27.7
Al
8.1
Fe
5.0
Ca
3.6
K
2.8
Mg
2.1
others
1.7

Categories of mineral
silicate minerals
Olivine
Pyroxene
Amphibole group (hornblende)
                Micas – biotite
                           muscouite
                feldspar – orthodase
                           -Ca, Na
quartz

ores – minerals that can be used by profit

Non silicate
Mineral group
name
use
oxides
hematite
Ore of iron
magnetite
corundum
gemstone
ice
Solid from of water
sulfides
galena
Ore of lead
sphalerite
Ore of zinc
pyrite
Sulphuric acid
chalcopyrite
Ore of copper
cinnabar
Ore of Hg
sulfades
gypsum
plaster
anhydrite
Native elements
gold
Trade, jewelry
copper
Electrical conductor
diamond
Gemstone, abrasive
sulfur
Sulfa drugs, chemical
graphite
Pencil leads, dry lubricants
silver
jewelry
platinum
catalyst
halides
halite
Common salt
flouride
Used in steel making
sylvite
fertilizer
calcite
cement
dolomite

Rock cycle
Lava – exterior (less dissolved substances)
Magma – interior

Driving force
-earth’s interior
-energy from the sun

Igneous rock – originates at depths as great , consist primarily as silicates

Classess:
Where it is formed
Volcanic/ extrusive igneous- exposed outside, rock that results when lava solidifies
Plutonic/ intrusive igneous – formed inside the earth’s surface, rocks form when magma solidifies
Crystal sizes (texture)
Fine grains – igneous rocks that form rapidly at surface as small masses within the upper crust
Coarse grains – magma solidifies far below the surface
Pophyritic – molten materials crystallizes outside. If magma that already contains some large crystals, suddenly erupts at the surface, the remaining molten portion of the lava would cool quickly.
Glassy – ejected in the atmosphere and quenhed rapidly

Kinds of sedimentary rocks
Detrital sedimentary rocks – originated from weathere rocks
Large particles –
Conglomerate- rounded
Breccias- angular
Small  particle
Sandstone – sand size
Siltstone – fine particles
Shale – very fine

Chemical sedimentary
-formed due to chemical process ex. Chalk, coqina, taventine, quartz, coal, limestone

Lithification -  process by which sediments are transformed into sedimentary rocks..
Compaction
Cementation

Features:
Strata or bed
Fossils
Provides info about past environment

Metamorphic rocks
Metamorphism
Regional metamorphism – due to intense stress and high temperature associated with large scale deformation
Contact – in contact / near the mass of magma

Metamorphic agent
Heat – when rock at the surface becomes in contact with a hot molten material, such as lava
Pressure – decreases the volume ; differential stress- unequal force
Chemically active fluid – ex. Water


Classification of metamorphic ricks
Foliated – parallel alignment of crystals
Ex. Gneiss –feldspar
Slate and schist – shale
Non foliated – ex. Marble

External process
-occurs near or at the earth’s surface powered by the sun
1. weathering – disintegration of rock materials
2. mass wasting – movement of debris downslope
3. erosion – transportation of material with the help of erosional agent
Weathering –
Mechanical weathering – broken into pices each retaining the characteristics of the original
Frost wedging – continuous cycle  and freezing of water
Unloading
Biological activity
Chemical weathering – change in the composition , involves that alters  structure of mineral


Soil – the interface of all spheres of the earth
Controls of soil
Parent material – source
Climate – temperature and humidity
Time – the longer the time, the more soil is formed
Plants and animals
Slope
Soil texture
Sand >silt>clay

Soil profile
0 horizon – consist of loargely organis material ; upper portion is primarily plant
Lower portion is made up of partly decomposed organic matter
A horizon – largely mineral matter
E horizon – zone of elevation
B horizon - subsoil; zone of accumulation
C horizon – partially altered parent material

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