MineralNaturally formed inorganic substance with a particular

chemical composition and a regularly repeating internal structure. Either in their perfect crystalline form or otherwise, minerals are the constituents of rocks. In more general usage, a mineral is any substance economically valuable for mining (including coal and oil, despite their organic origins).

Classification of Minerals

Magmatic – These includes the feldspars, quartz, pyroxenes, amphiboles, micas, and olivines that crystallize from silica-rich rock melts within the crust or from extruded lavas.

Sedimentary – the most commonly occurring sedimentary minerals are either pure concentrates or mixtures of sand , clay minerals, and carbonates (chiefly calcite, aragonite, and dolomite).

Metamorphic - these minerals include andalusite, cordierite, garnet, tremolite, lawsonite, pumpellyite, glaucophane, wollastonite, chlorite, micas, hornblende, staurolite, kyanite, and diopside.

RocksAre solid pieces of the Earth or any other inorganic body

in the Solar System. They are composed of minerals or materials of organic origin.

Types of Rocks

Igneous Rock

Sedimentary Rock

Metamorphic Rocks

Igneous Rocks

formed by the cooling and solidification of magma, the molten rock material that originates in the lower part of the Earth’s crust, or mantle, where it reaches temperatures as high as 1,000°C.

Common Igneous Rocks

volcanic(porous or glassy)

obsidian scoria pumice

volcanic(fine-graned)

rhyolite andesitebasalt

plutonic(coarse-graned)

granite diorite gabbro

Sedimentary Rock are formed by the comprehension of particles

deposited by water, wind, or ice. They may be created by the erosion of older rocks, the deposition of organic materials, or they may be formed from chemical.

Common Sedimentary Rocks

Clastic

sandstone shale conglomerate

Chemical

fine-grained limestone agate (microcrystalline quartz)

Organic

coal limestone

Metamorphic Rocks

are formed through the action of high pressure or heat on existing igneous or sedimentary rocks, causing changes to the composition, structure, and texture of the rocks.

Common Metamorphic Rocks

quartzite marble gneiss (& garnet crystals)

Rock StudiesThe study of the Earth’s crust and its composition

fall under a number of interrelated sciences, each with its own specialist. Among these are:

Geologists - who identify and survey rock formations and determine when and how they were formed.

Petrologists – who identify and classify the rocks themselves,.

Mineralogists – who study the mineral contents of the rocks.

Palaeontologists – study the fossil remains of plants and animals found in rocks.

The Earth’s Interior

Our planet is the third planet from the sun. it is almost spherical, flattened slightly at the poles, and is composed of five concentric layers: inner core, outer core, mantle, crust, and atmosphere. About 70% of the surface (including the north and south polar icecaps) is covered with water.

Mean distance from the Sun: 149,500,000 km

Equatorial diameter: 12,755 km

Circumference: 40,070 km

Rotation period: 23 hr 56 min 4.1 sec

Year: 365 days 5 hr 48 min 46 sec. Earths average speed around the sun is 30 kps/18.5 mps; the plane of its orbit is inclined to its equatorial plane at an angle of 23.5°, the reason of unchanging seasons

Atmosphere: nitrogen 78.09%; oxygen 20.95%; argon 0.93%; carbon dioxide 0.03%; and less than 0.0001% neon, helium, krypton, hydrogen, xenon, ozone

Surface: land surface 150,000,000sq km (greatest height above sea level 8,872m Mount Everest); water surface 361,000,000sq km/139,400,000sq mi (greatest depth 11,034m/36,201ft Mariana Trench in Pacific). The interior is thought to be an inner core about 2,600km/1,600ml in diameter, of solid iron and nickel; an outer core about 2,250km/1400mi thick, of molten iron and nickel; and mantle of mostly solid rock about 2,900km/1,800mi thick.

Satellite: Moon

Age: 4.6 billion years. The earth was formed with the rest of the Solar System by consolidation of interstellar dust. Life begun 3.5-4 billion years ago.

Divisions in the Earth's Interior (Adapted from, Beatty, 1990.)

The Earth’s CrustThe crust is a rocky outer layer of earth, consisting of

two distinct parts, the oceanic crust and continental crust.

Oceanic crust – This part is on average about 10km thick and consists mostly of basaltic rock overlain by muddy sediments.

Continental crust – it is largely of granitic composition and is more complex in its structure. Because it is continually recycled back into the mantle by the process of subduction.

 

The CoreThe core is the innermost part of the earth. It is divided

into an outer core, which begins at the depth of 2,900km, and the inner core, which begins at a depth of 4,980km. both parts are thought to consist of iron nickel alloy. The outer core is liquid and the inner core is solid.

Inner core: 1.7% of the Earth's mass; depth of 5,150-6,370 kilometers (3,219 - 3,981 miles)

Outer core: 30.8% of Earth's mass; depth of 2,890-5,150 kilometers (1,806 - 3,219 miles)

D": 3% of Earth's mass; depth of 2,700-2,890 kilometers (1,688 - 1,806 miles)

Lower mantle: 49.2% of Earth's mass; depth of 650-2,890 kilometers

(406 -1,806 miles)

Transition region: 7.5% of Earth's mass; depth of 400-650 kilometers (250-406 miles)

Upper mantle: 10.3% of Earth's mass; depth of 10-400 kilometers (6 - 250 miles)

Oceanic crust: 0.099% of Earth's mass; depth of 0-10 kilometers (0 - 6 miles)

Continental crust: 0.374% of Earth's mass; depth of 0-50 kilometers (0 - 31 miles).

Earthquake

An abrupt motion that propagates through the earth and along its surfaces is called earthquake. Earthquakes are caused by the sudden released in rocks of strain accumulated over time as a result of tectonics. The study of earthquakes is called seismology. The force of earthquakes (magnitude) is measured on the Richter scale, and their effect (intensity) on the Mercalli scale. The point at which an earthquake originates is the seismic focus or hypocenter; the point on the earth’s surface directly above this is the epicenter.

Earthquakes happen as large blocks of the Earth’s crust move suddenly past one another because of the force of plate tectonic. These blocks of the Earth’s crust meet at cracks called faults. Sometimes those pieces do not slide smoothly past one another. There can be friction along the fault – jagged edges that snag the blocks of rock. This makes it difficult for them to move past each other. Sometimes they get stuck together temporarily. When the pieces of rock overcome the snags, energy is released. The release of energy causes shaking at the ground surface.

The location inside the Earth where an earthquake begins is called the focus. The point at the Earth’s surface directly above the focus is called the epicenter. The strongest shaking happens at the epicenter.

Description of the 12 levels of the Modified Mercalli intensity scale:

I. Not felt except by a very few under especially favorable conditions.

II. Felt only by a few persons at rest, especially on upper floors of buildings.

III. Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibrations similar to the passing of a truck. Duration estimated.

IV. Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably.

V. Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop.

VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.

VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.

VIII. Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.

IX. Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations.

X. Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent.

XI. Few, if any (masonry) structures remain standing. Bridges destroyed. Rails bent greatly.

XII. Damage total. Lines of sight and level are distorted. Objects thrown into the air.

Some of the Major Earthquakes Since 1980Date Location Magnitude

(Richter scale)Estimated number of

deaths10 October

1980Northern Algeria 7.2 4,800

19,21 September

1985

Mexico City, Mexico 8.1 5,000

7 December 1988

Armenia 6.8 25,000

20-21 June 1990

Northwestern Iran 7.7 50,000

16 July 1990 Luzon, Philippines 7.7 1,660

29 September 1993

Maharashtra, India 6.3 9,800

16 January 1995

Kobe, Japan 7.2 5,500

17 August 1999

Turkey 7.4 14,095

21 September 1999

Taiwan 7.6 2,256

FaultA planar break in rocks, along which the rock

formations on either side have moved relative to one another called fault. Fault involve displacements, or offsets ranging from the microscopic scale to hundreds of kilometers. Large offsets along a fault are the result of the accumulation of smaller movements (meters or less) over long periods of time. Large motions cause detectable earthquakes

Faults produce lines of weakness on the Earth’s surface (along their strike) that are often exploited by processes of weathering and erosion. Coastal caves and geos (narrow inlets) often form along faults and, on a larger scale; rivers may follow the line of a fault.

Types of Fault

Normal Faults – these occur when the hanging wall moves down relative to the footwall. It occur where rocks on the either side have moved apart.

- It happen in areas where the rocks are pulling apart (tensile forces) so that the rocky crust of an area is able to take up more space.

- The rock on one side of the fault is moved down relative to the rock on the other side of the fault.

- Normal faults will not make an overhanging rock ledge.

In a normal fault it is likely that you could walk on an exposed area of the fault.

Reverse Faults – these happen where the hanging wall has moved up relative to the footwall. A reverse fault that forms low angle with the horizontal plane is called a thrust fault. It occurs where the rocks on either side have been forced together.-Reverse faults happen in areas where the rocks are pushed

together (compression forces) so that the rocky crust of an area must take up less space.

-The rock on one side of the fault is pushed up relative to rock on the other side.

-In a reverse fault the exposed area of the fault is often an overhang. Thus you could not walk on it.

• Lateral fault or strike – slip fault – the occurrence happens where the relative movement along the fault plane is sideways.

• Transform Fault – it is a major strike – slip fault along a plate boundary, that joins two other plate boundaries – two spreading centers, two subduction zones, or one spreading center and one subduction zone.

-The movement along a strike slip fault is horizontal with the block of rock on one side of the fault moving in one direction and the block of rock along the other side of the fault moving in the other direction.

- strike slip faults do not make cliffs or fault scarps because the blocks of rock are not moving up or down relative to each other.

Normal dip-slip fault

Reverse dip-slip fault

Transform (strike-slip) faults

Seismic Wave

Seismic wave is the energy wave generated by sn earthquake or an artificial explosion.

Types of Seismic Waves

Body waves – Seismic waves that travel through the Earth’s interior.

P - Waves or Primary Waves – longitudinal waves whose compressions and refractions resemble those of the sound wave.

S - Waves or Secondary Waves – transverse waves or shear waves that involve a back and forth shearing motion at the right angles to the direction the wave is traveling.

L - Waves or Love waves – these waves are transverse waves and considered the slowest since it trapped in a subsurface layer due to different densities in the rock layers above and below. They have a horizontal side – to – side shaking motion transverse (at right angles) to the direction wave is traveling.

Surface Waves – Surface waves travel in the surface and subsurface layers of the crust.

Rayleigh waves – surface that travel along the free surface (the uppermost layer) of a solid material. The motion of particles is elliptical, like a water wave, creating rolling motion often felt during an earthquake.

typical seismogram (Figure)

Plate Tectonic A theory formulated in the 1960s to explain the

phenomena of continental drift and seafloor spreading, and the formation of the major physical features of the Earth’s surface. The Earth’s outermost layer, the lithosphere, is regarded as a jigsaw puzzle of rigid major and minor plates that move relative to each other, probably under the influence of convection currents in the mantle beneath. At the margins of the plates, where they collide or move apart or slide past one another, major landforms such as mountains, rift valleys, volcanoes, ocean, trenches, and ocean ridges are created. The rate of plate movement is at most 15 cm/6in per year.

There are 3 types of Plate Boundaries; Constructive margins (Diverging Boundaries), Destructive margins (Converging Boundaries), and Conservative margins (Transform fault)

Constructive margins (Diverging Boundaries) – Where two plates are moving apart from each other, molten rock from the mantle wells up in the space between the plates and hardens to form crust, usually in form of an ocan ridge (such as the Mid – Atlantic Ridge). The newly formed crust accumulates on either side of the ocean ridge causing the seafloor to spread; the floor of the Atlantic Ocean is growing by 5cm or 2in each year because the welling up of new material at Mid – Atlantic Ridge.

Destructive margins (Converging Boundaries) – where two plates are moving towards each other, the denser of the two plates may be forced under the other into a region called the subduction zone. The descending plate melts to form a body of magma, which may then rise to the surface through cracks and faults to form volcanoes. If the two plates consist of more buoyant continental crust, subduction does not occur. Instead, the crust crumples gradually to form ranges of young mountains, such as the Himalayas in Asia, the Andes in South America, and the Rockles in North America. This process of mountain building is termed orogenes.

Conservative margins (Transform fault) – sometimes two plates will slide past each other – an example is the San Andreas Fault, California, where the movement of the plates sometimes takes the form of sudden jerks, causing the earthquakes common in the san Francisco – Los Angeles area. Most of the earthquake and zones of the world are found in regions where two plates meet or are moving apart.

Causes of Plate Movement

It has been known for some time that heat flow from the interior of the earth is high over the mid – ocean ridges, and so various models of thermal convection in the mantle have been proposed;

  The geometry of the flow in any convective system must be

complex, as there is no symmetry to the arrangement of ridges and trench systems over the Earth’s surface. It seems likely that plume of hot, molten material rises below the ridges and is extruded as basaltic lava.

In zones of descending flow, at deep ocean trenches, the surface sediment is scraped off the descending plate onto the margin of the static plate, causing it to grow outwards towards the ocean while the basaltic rocks of the descending plate, together with any remain ing sediment, suffer partial fusion as they descend. This gives rise to large volumes of molten rock material, or magma, which ascend to form andesitic lavas and intrusions of diorite or granodiorite at the margin of the overlying continent.