2. 1.The superficial unconsolidated and
usually weathered part of the
earth’s crust
2.The upper layer of earth that may
be dug or plowed and in which
plants grow.
3. .
Minerals make up rocks.
Natural compounds
and elements combine
to form minerals.
Elements combine to form
the natural compounds.
Rocks make up the Earth.
There is a hierarchy to the
elements of Geology
Atoms make up elements.
4. Diagram of the Interior of the Earth
Crust
0 to 40 km
Surface Temp atm.
Upper Mantle
40 to 670 km
1,000°C
Lower Mantle
670 to 2,890 km
2,000°C
Outer Core
2,890 to 5,150 km
3,700°C
Inner Core
5,150 to 6,370 km
4,300°C
SOIL, a thin skin
few cm to meter
5. The definition of a soil vary depending on how the soil is used by
a person. To a
1. Mining Engineer: Soil is the debris covering the rocks or
minerals which s/he must quarry.
2. Highway Engineer: Soil is material on which a roadbed is to be
placed.
3. Pedologist (interested about origin of soil) : Soil is natural body
on the Earth’s surface consisting of mineral and organic
material that changes, or has changed due to action of climate
and living organism.
4. Farmer: Soil is a place which she/he can use to produce food
and fiber.
All of them are correct in their own sense.
But, as an agriculture scientist, let us define and understand a
soil in the perspective of growing crops.
6. Definition-I
The unconsolidated mineral or
organic material on the
immediate surface of the earth
that serves as a natural medium
for the growth of land plants.
7. Definition -II
Soil is a natural body comprised of solids
(minerals and organic matter), liquid, and
gases that occurs on the land surface,
occupies space, and is characterized by
one or both of the following: horizons, or
layers, that are distinguishable from the
initial material as a result of additions,
losses, transfers, and transformations of
energy and matter or the ability to support
rooted plants in a natural environment.
8. What are the functions of soil?
• Medium for Growing Plant
• Recycling system for nutrients,
organic matter
• Home for many Animal
• System for water supply and
purification
• Engineering medium
(for construction of road,
building, bridges, factory
etc.)
17. Effect of Soil Structure on other Physical Properties:
Porosity
Porosity of a soil is easily changed. In plate like structure, pore
spaces are less where as in crumby structure pore spaces are more.
Temperature
Crumby structure provides good aeration and percolation of water in
the soil. Thus these characteristics help in keeping optimum
temperature in comparison to plate like structure.
Density:
Bulk density varies with the total pore space present in the soil.
Structure chiefly influences pore spaces Platy structure with less
total pore spaces has high bulk density where as crumby structure
with more total pore spaces has low bulk density
Consistence
Consistence of soil also depends on structure. Plate-like structure
exhibits strong plasticity.
Colour
Bluish and greenish colors of soil are generally due to poor drainage
of soil. Platy structure normally hinders free drainage..
18. The role of soil structure in relation to plant growth
Soil structure influences the amount and nature of porosity.
Structure controls the amount of water and air present in the soil.
Not only the amount of water and air dependent on soil structure, but
their movement and circulation are also controlled by soil structure.
It affects tillage practices.
Structure controls runoff and erosion.
Platy structure normally hinders free drainage whereas sphere like
structure (granular and crumby) helps in drainage.
Crumby and granular structure provides optimum infiltration, water
holding capacity, aeration and drainage. It also provides good habitat
for microorganisms and supply of nutrients.
23. An E horizon can
develop in this
area.
Bedrock can lie
below the C
horizon. In this
position, the
bedrock is called an
R horizon.
24. Soil Horizons
O horizon – mostly organic material
A horizon – Topsoil – dark color, lots of
organics.
B horizon – deposition of material (iron,
aluminumleached out of the E horizon
(iluviation)
R horizon – Regolith (Weathered bedrock)
E horizon – Lighter colored because of
dissolution of minerals by water moving
downward (leaching/eluviation) (Quartz
sand left behind is lighter colored.
26. Soil profile
O horizon – mostly organic material
A horizon – Topsoil, dark color,
lots of organics.
B horizon – deposition of material
(iron, aluminumleached out of the E
horizon (iluviation)
R horizon – Regolith (Weathered
Bedrock)
E horizon – Lighter colored because of
dissolution of minerals by water moving
downward (leaching/eluviation) (Quartz
sand left behind is lighter colored.
27. Atomic Theory proposes that all matter is composed of the atoms
of about 100 different chemical elements. It further proposes that
chemical compounds are formed by the combination of the atoms
of different chemical elements. Elements can be arranged, based
on their identifiable properties, into the Periodic Table
Only eight elements make up over 98% of the earth’s crust!
#3:Here the intent is to show how the various pieces; atoms, elements, compounds, and minerals, rocks and even the Earth, are related to each other in a hierarchy.
Classroom exercise- Take some road salt (larger pieces of rock salt used to melt ice and snow) and have the students look at them and describe what they see. A magnifying glass is very handy here. Students should note blocky nature made up of various sizes of blocks or cubes. As appropriate, note the differences between 2 dimensional references like square or circle and 3 dimensional references like block, cube and sphere.
This will require three samples of rock salt that will be broken to show the physical characteristics of a mineral. With goggles on to protect the eyes, have a student gently tap sample 1 with a metal spoon (or some other relatively heavy blunt object) and observe what happens (salt/halite cleaves or breaks into many smaller blocks or cubes). On a sample 2 use a butter knife placed diagonally on one of the faces of a salt block and gently tap edge of the knife blade. What happens? (results is similar to the spoon maybe fewer small pieces) On sample 3 use a butter knife placed parallel to the sides about in the middle of a piece of salt and gently tap edge of the knife blade. What happens? (Fewer, cleaner breaks / fewer pieces because energy was direct more specifically along the cleavage planes in the rock salt. - much like a diamond cutter does when the start working on a new diamond).
How many crystal faces are there on a cube - how many directions of cleavage are there What is the angular relationships. Examine regular table salt with a hand lens and describe what you see. Grow crystals from salt water or sugar water - have students dissolve the sugar or salt in water - how can they tell when they have added ‘enough?’ When the salt or sugar does not dissolve any more but goes right to the bottom of the glass - what happens with mixture is heat? (supersaturated solution). Try a mixture of salt and sugar to see what happens. What other household materials could be used to grow crystals (alum, Epson salts …). Students should observer the crystal growing experiment daily and record their observations. Have students explain how the terms dissolve, mixture, precipitate and crystal relate to the crystal growing exercise. Another variation is to have students place their crystal growing containers in different locations – sunny window sill, on heat register, in a storage closet and have them discuss what effect the location had on the outcome of their experiment.
For even more go to GEOMAN’s page @ http://jersey.uoregon.edu/~mstrick/index.html
Created October 2, 2000, revised September 2001
#4:Crust – The ‘outer’ layer consisting of the part of the earth we live on.
0 to 40 km (0 to 25 miles) - 0°C (32°F) - - The upper 100-200 kilometer (km) of the Earth, consisting of the crust and uppermost mantle is characterized by a geothermal temperature gradient of 20-30 °C per kilometer (40-50 °F per mile).
The part of the mantle near the crust, about 50-100 km down, is especially soft and plastic, and is called the asthenosphere. The mantle and crust above are cool enough to be tough and elastic, and are known as the lithosphere.
Mantle - A rock layer that reaches about half the distance to the center of the earth. Parts of this layer become hot enough to liquefy and become slow moving molten rock or magma.
Upper Mantle - - 40 to 670 km (25 to 415 miles) - 1,000°C (1,800°F)
Lower Mantle - - 670 to 2,890 km (415 to 1,800 miles) - 2,000°C (3,600°F)
Outer Core - - A mass of molten iron that surrounds the solid inner core. Electrical currents generated from this area produce the earth's magnetic field.
2,890 to 5,150 km(1,800 to 3,200 miles) - 3,700°C (6,700°F)
Inner Core - - A mass of solid iron. Although ambient temperatures would normally melt iron, the immense pressure on it keeps it in a solid form. This concentration of mass is partially responsible of determining how fast the Earth rotates. (spinning a fresh egg vs.. a boiled egg or the spinning skater – conservation of angular momentum)
5,150 to 6,370 km (3,200 to 3,960 miles) - 4,300°C (7,500°F)
Have students use work sheets to reinforce information about layers of the earth.
Measurements can and do vary from one source to another due difference in definitions, when the work was done, quality and quantity of supporting information and procedures used to extrapolate the data.
http://wwwneic.cr.usgs.gov/neis/plate_tectonics/plate_tectonics.html
Created October 2, 2000
#28:Here is a good point to help students see the links between chemistry and geology. How many elements are there? Well are we talking just naturally occurring, or naturally occurring and those made readily in the lab, do we include those that are very unstable and do not exist in nature (at least for any length of time) and what about the elements that exist ‘on paper only’ and just who/what is the source that decides into which category an element might be classified?
Whatever the count there is an order to the arrangement and each element has its own set of uniquely identifiable properties or characteristics.
Reinforce the relationship between atoms, elements and compounds.
Created October 2, 2000
