Naming Igneous Rocks Classified by

Naming Igneous Rocks
 Classified by texture and mineral
composition.
 Granitic
 Andesitic
 Basaltic
 Ultramafic35
Basalt
 Calcium-rich
 The most common
extrusive igneous
rock.
 From volcanic.
http://media.photobucket.com/image/Basalt/myownslave/basalt.jpg36
Granitic
 Quartz
 Potassium feldspar
 by-product of
mountains.
http://www.thaigoodview.com/files/u2578/imagesCABGGEDW.jpg http://library.thinkquest.org/05aug/00461/images/granite.jpg37
Andesite
 A five-grained
volcanic rock.
 Has a mineral
composition
between that of
granitic and
basaltic rock.
http://geology.com/rocks/pictures/andesite.jpg38
Classifying Sedimentary Rocks
 Two principal sources
1. Solid particles from weathered rocks called
“detrital sedimentary rocks”
2. Soluble material from chemical weathering
called “chemical sediments rocks” derived
from material.39
Detrital Sedimentary Rocks
According to its particle size and. Conglomerate
 Gravel(กรวด) Breccias
 Sand(ทราย) Sand stone
 Mud(โคลน) Shale(หินชั้น)40
Gravel
 Gravel is rock that is of a
specific particle size range.
 In geology, gravel is any loose
rock that is larger than two
millimeters (2mm) in its largest
dimension (about 1/12 of an
inch) and no more than 63
millimeters (about 2.5 inches).
 Sometimes gravel is restricted to
rock in the 2-4 millimeter range,
with pebble being reserved for
rock >4-63 millimeters. http://crushercn.files.wordpress.com/2009/02/gravel.jpg41
Gravel : Breccias
 Breccia is a clastic
sedimentary rock that is
composed of large (over two
millimeter diameter) angular
fragments.
 The spaces between the
large fragments can be filled
with a matrix of smaller
particles or a mineral cement
which binds the rock
together.
 The specimen shown above
is about two inches (five
centimeters) across.
http://geology.com/rocks/breccia.shtml42
Sand : Sand stone
 Sandstone is a classic
sedimentary rock made
up mainly of sand-size
(1/16 to 2 millimeter
diameter) weathering
debris.
 Environments where
large amounts of sand
can accumulate include
beaches, deserts, flood
plains and deltas.
http://geology.com/rocks/sandstone.shtml43
Mud : Shale
 Shale is a clastic
sedimentary rock that is
made up of clay-size
(less then 1/256
millimeter in diameter)
weathering debris.
 It typically breaks into
thin flat pieces.
http://geology.com/rocks/shale.shtml44
Classifying Metamorphic Rocks
 Foliated Rocks
 Non foliated Rocks.45
Soil, Soil Horizon,
and Soil type46
Soil
 Bedrock breaks into smaller fragments as it
weathers, and much of it decomposes to clay
and sand.
 Therefore, on most land surfaces, a thin layer
of loose rock fragments, clay and sand
overlies bedrock.
 This material is called regolith.47
Components of Soil
 Soil is a mixture of mineral grains, organic
material, water, and gas.
 The mineral grains include clay, silt, sand and
rock fragments.
 Clay is so fine-grained and closely packed
that water, and even air, do not flow through
a clay-rich soil readily, so plants growing in
clay soils suffer from lack of oxygen.48
Components of Soil
 In contrast, water and air flow easily through
sandy soil.
 The most fertile soil is loam, a mixture of
sand, clay, silt, and generous amounts of
organic matter.
 Bits of leaves, stems, and flowers on the soil
surface is called litter.
 When litter decomposes sufficiently that you
can no longer determine the origin of
individual pieces, it becomes humus.49
Components of Soil
 Humus is an essential component of most
fertile soils.
 Allowing roots to grow into it easily.
 Insulates the soil from excessive heat and cold
and reduces water loss by evaporation.
 Retains soil nutrients and makes them available to
plants.50
Soil Horizons
 Soil consists of several layers called soil
horizons. Soil horizons consist of…
 O Horizon
 A Horizon
 B Horizon
 C Horizon
 Bedrock51
Soil Horizons:
Diagram
http://img.sparknotes.com/figures/A/a4d938a405b10475f48eea440b31bab3/Soil_Horizons.jpg
 O : Topsoil
 Organic matter(humus)
 Living organisms
 A : Zone of leaching
 Dissolved or suspended
 Material move downward
 B : Zone of accumulation
 Zone of deposition
 Accumulate of iron, aluminum, and
clay
 Leached down from the A horizon;
 Contains soluble minerals like calcite
in drier climates.
 C : Weathered parent material
 Partially broken down
 Bedrock52
O Horizon
 The uppermost layer
is called the O
horizon
 Organic
component…Litter+H
umus with small
proportion of mineral.
 Fig. 10.14
http://www-markinfo.slu.se/sve/mark/jman/bilder/overg5m.jpg53
A Horizon
 A Horizon is a mixture of humus, sand, silt, and
clay.
 The combination of O and A horizons are called
topsoil
http://www.emporia.edu/earthsci/student/laird3/soilpic4.jpg54
Leaching process
 Leaching process : precipitation infiltrates down
through the A horizon then…the water may dissolve
soluble minerals and carry them away with it.
 1 kg of topsoil consist of
 2 trillion bacteria
 400 million fungi
 50 million algae
 30 million protozoa
 1,000 of larger organisms such as insects, worms,
nematodes, and mites.55
Leaching process
 When rain falls on soil, it sinks into the O and
A horizons,
 Weathering minerals, forming clay, and
carrying dissolved ions to lower levels.
 This downward movement of water and
dissolved ions is called leaching.56
B Horizon
 The third layer, the B
horizon or subsoil, is a
transitional zone between
topsoil and weathered
parent rock below.
 Roots and other organic
material grow in the B
horizon, but the total
amount of organic matter
is low.
http://pubs.usgs.gov/gip/capecod/images/fig17200.jpg57
C Horizon
 The lowest layer,
called the C horizon.
 Consists of partially
weathered rock that
grades into
unweathered parent
rock.
 Contains little organic
matter.
http://www.uwsp.edu/soils-waste/slevine/soils362/lectures/aridisol12.jpg58
Soil-Forming Factors
 Six factors control soil characteristics.
1. Parent rock
2. Climate
3. Rate of plant growth and decay
4. Slope aspect and steepness
5. Time
6. Transport of soil materials.59
Soil-Forming Factors:
1. Parent rock
 The texture and composition of soil depend
partly on its parent rock.
 Granite decomposes, the feldspar converts to
clay and the rock releases quartz as sand
grains.60
Soil-Forming Factors:
2. Climate
 Rainfall and temperature affect soil formation.
 Average annual temperature, affects soil
formation in two ways.
 Chemical reactions proceed more rapidly in
warm temperatures than in cold ones.
 Plant growth and decay are temperature
dependent.61
Soil-Forming Factors
3. Rates of plant growth and decay
 Plant grow and decay rapidly increase litter
and humuss.
http://www.rvtravelog.com/quoddyhead.dir/image04.jpg62
Soil-Forming Factors
4. Slope aspect and steepness
 Aspect is the orientation of a slope with
respect to the sun.
 Hill sides have thin soils and valleys are
covered by thicker soil.
 Because soil erodes from hills and
accumulates in valleys.63
Soil-Forming Factors
5. Time
 Young soils, weathering may be incomplete
and the soils may contain many partly
weathered mineral fragments.
 As a result, young soils are often sandy or
gravelly.64
Soil-Forming Factors
6. Transport of soil materials