ondernotes
NATURal Science II
Geology 1st Sem, 1st Exam
Geology
 Geo(earth) + logos(discourse/study)
 “science of the earth”
o Materials (minerals, rocks, etc.)
o Processes (weathering, sedimentation, etc.)
o Products (soil, etc.)
 History of the planet’s life forms since its origin
 The study of the Earth and other such solid bodies in space (moons, Mars, etc.)
 It’s beginning is lost in antiquity
 Modern geology was born in 1788
 Major branches:
o Historical Geology:
 History of the earth and it’s life forms
 Ex. stratigraphy, paleontology, geochronology, etc.
o Physical Geology:
 Deals with the materials and processes
 Ex. seismology, volcanology, mineralogy, petrology, etc.
 Eclectic science (takes what is needed from various fields like biology and chemistry)
 Demonstrated the immensity of time
 Geologic mapping
 Studies background for evolution of life
 Applications:
o mitigation of natural disasters
o environmental impact assessment
o foundation stability
o utilization of natural resources
o unraveling the history of life
 sub-fields:
o
stratigraphy – earth’s layers
o
petrology – rocks
o
paleontology – life’s history
o
geomorphology – land forms
o
geochronology – sequencing events o
seismology – earthquakes
o
crystallography – crystals
o
volcanology – volcanoes
o
mineralogy – minerals
o
structural geology – folds, faults, etc.
UNIFORMITARIANISM
 the physical, chemical and biological features of the earth were produced by the same processes that
occur today
 the laws of nature are unchangeable
 James Hutton (Father of Modern Geology) “Modern Geology, I am your father!”
o “Theory of the Earth’s Transactions of the Royal Society of Edinburgh”, 1788
o The history of the earth is composed of geologic cycles
o Cycles have no beginning or end
o Evidence:
 Outcrop of Siccar Point, Burwickshire
 A geologic cycle occurs, creating differently tilted rock layers
 The present is the key to the past!
 The Earth changes, but only in accordance to unchanging physical laws
 Uniformity of process but not of rate, time, nor place of occurrence
CATASTROPHISM
 Earth’s history is a series of catastrophes
 Each catastrophe exterminated existing life
 Baron Georges Cuvier
o Six major catastrophes (6th = Great Deluge [Noah’s Ark])
o Evidence:
 Paris Basin layers of fossils, where fossils in one layer no longer in the next
 DISPROVED – in other places, fossils are mixed!
THE UNIVERSE
 All energy and matter that exists
 Big Bang (14-15 BYA)
o Event filling all of space with the particles of the embryonic universe rushing away from
each other
 Nebular Hypothesis
o Solar system from nebula(cloud of gas and dust)
o Contracts to a rotating disk heated by gravitational energy converted to thermal energy
o Cooling results in the formation of rocky and metallic materials condensing into smaller
particles
o Collisions caused merging, and change of size from dust size to asteroid size
o Fragments accrete to form planets
EARTH’s sIZE And sHAPE
 Eratosthenes – Greek mathematician, geographer, astronomer
o Geodesy – branch of applied math dealing with the measurement of large areas or the Earth
using variations in gravity and the distance of known points
o Observations:
 Shorter shadows at the equator
 Alexandria well – part in shadow during summer solstice
 Aswan(Syene) well – no shadow in well at noon
 Alexandria is 925 km north of Aswan
o Assumptions:
 The sun is so distant, its rays on both places are parallel
 A plane passing through Aswan, Alexandria, and the noon sun would pass through
the center of the earth
 The plumb line points directly towards the earth’s surface
 The east and west walls of Alexandria lie on the north-south planes
 The earth is a sphere
o Conlusion:
[𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒(𝑎𝑠𝑤𝑎𝑛−𝑎𝑙𝑒𝑥𝑎𝑛𝑑𝑟𝑖𝑎) ][3600 ]

Polar circumference = [𝑎𝑛𝑔𝑙𝑒 𝑜𝑓 𝑠𝑢𝑛′ 𝑠 𝑟𝑎𝑦𝑠 𝑡𝑜 𝑡ℎ𝑒 𝑣𝑒𝑟𝑡𝑖𝑐𝑎𝑙] = 450k ~ 470k km

14% larger than true measurement (40,008 km)
 Why?
o Assumption that Alexandria is directly north of Aswan
o Aswan is not precisely upon the Tropic of Cancer
 17th and 18th century
o Eratosthenes’ method was resurrected
o north – south lines or arcs of meridian were measured at different latitudes(Finland, France,
Peru)
o when compared, latitude in Finland > latitude in Peru
 why? Because Earth is not a sphere, it is an oblate spheroid
 International Union of Geodesy and Geophysics (1967)
o Polar diameter – 12,713.54 km
o Equatorial diameter – 12,756.32 km
o Polar circumference – 40,008.00 km
o Equatorial circumference – 40,075.16 km
THE EARTH’s OUTER LAYERs
 Atmosphere
o 78% hydrogen, 21% oxygen, 1% argon, other gases
o Original atmosphere
 Methane, ammonia, water, hydrogen
 What happened? (Anyare?!) – blown into space, swept away by solar wind
o Second atmosphere
 Made from frozen gases trapped in Earth’s interior/chemical compounds in rocks
 Released through outgassing by volcanoes, fissures, fumaroles
 Water vapor, carbon dioxide, carbon monoxide, nitrogen, hygrogen
 Where did oxygen come from?
 Primitive photosynthesis by cyanobacteria
 Water vapor became O2 through photochemical dissociation (chemical
action of light)
 Existing O2 reacted with ammonia and methane, producing more oxygen
 Where did liquid H2O come from?
 Water vapor -> clouds -> precipitation
 Hydrosphere
o Earth – blue planet/water planet
o Water is in constant motion (hydrologic cycle)
o Global ocean
 Most prominent feature of earth
 70.8% (361,059,000 km2) of earth’s surface
 98% of all earth’s water
* land makes up 29.2% (148,892,000 km2) of surface
 Northern hemisphere 4/5 land, land hemisphere
 Southern hemisphere 1/10 land, water hemisphere
 Biosphere
o All life on earth
o Exists in a narrow zone extending from photic zone to snowline in mountains
 Photic zone – sunlit area of ocean, 200-300 m below sea level
 Snowline – 6000 m above sea level
o Factors contributing to distribution:
 Temperature, pressure, chemistry
o Without life, the make-up and nature of other spheres would be different
o Latitudinal control (due to tilt)
 High altitude – warm water
 Low – mid latitude – cold water
CONTINENTS
 Roughly triangular
 Concentrated in Northern Hemisphere
 Appear to be remarkably flat
 3 major structural components
o Basement complex/shield
 Completely deformed rocks eroded down to sea level
 Ex. Canadian shield
o Stable platform
 Basement complex covered by layer/veneer of sedimentary rock
 Ex. Nashville, Tennessee
o Folded mountain belts
 Ex. Appalachian mountains
 Less dense than ocean basin
 Old – 3.8 BYA
 Climatic zone determines the type/style of landforms
 Granite, silicon, etc.
OCEAN BASINS
 Previously thought as nondescript
 Oceanic crust
o Mostly basalt – denser simatic(Si + Mg) crust
o Holds the key to the evolution of the earth’s crust
o Young in the geologic time frame (150 MYA)
 Major provinces
o Oceanic ridge system
 Most prominent mountain range on earth
 Formed from layers of molten rock
 Ex. Mid-Atlantic ridge/East Pacific rise
o Trenches
 Relatively narrow and extremely deep grooves/depressions
 Occurs in subduction zone
 Ex. Philippine trench
o Abyssal floor
 Vast area of broad, smooth deep ocean floor on both sides of ridges
 Harsh conditions = less diverse life
EARTH’s InTERIOR
 Information obtained from:
o P waves – move through all media
o S waves – solid medium only
 Layers:
o Crust

Felsic/mafic

5-40 km thick
o Mantle

Mafic



2885 km thick


Heterogeneous
~2.9 g/cm3
Homogeneous (Mg,Fe)SiO3 /
(Mg,Fe)O
~3.5-5.5 g/cm3

o
Core




Layered
 Upper mantle
o Dunite – ultramafic igneous rock (olivine)
o Peridotite – ultramafic igneous rock (pyroxene/olivine)
o Eclogile – mafic metamorphic rock
o Chrondite – unmodified rock from meteorites
 Transition zone
 Lower mantle
Rich in Fe
Minor amounts of S, Si, O, C, Ni
~5.5-13 g/cm3
2 regions
 Outer core – liquid, 2270 km thick, possible origin of magnetic field
 Inner core – solid, 1216 km radius
 Regions
o Lithosphere
 Slab of rock, variable thickness
 Upper boundary – crust
 Lower boundary – asthenosphere
 Mohorovicic Discontinuity
o Asthenosphere
 Low velocity zone (of seismic waves)
 Zone of partial melting
 Upper upper mantle
 Discontinuities
o Mohorovicic Discontinuity
 Boundary of crust and mantle
 Phase change from lower crustal to mantle rocks
 Basic to ultrabasic rocks
o Gutenberg – Wichert Discontinuity
 Boundary between mantel and core
 Heat sources
o Radioactivity of uranium, thorium, potassium
o Conversion of gravitational energy to thermal energy
o Reduction in pressure
 Sample Features:
o Seamount – formed when molten oceanic crust seeps through crustal fractures
o Islands - formed when the top of a seamount breaks the surface of the water
o Guyot – seamounts whose peaks are eroded / ‘flat top’
o
MINERALS
 Naturally occurring, Homogeneous, Inorganic
 Solid with ordered atomic arrangement / crystalline structure
 Definite chemical composition that may vary within ordered limits
 More than 4000 known minerals
MINERALOID
 Naturally occurring amorphous substance
 Without crystalline structure / orderly pattern of elements
CRYSTAL
 Regularly shaped object that reflect ordinary arrangement of internal structure
POLYMORPHISIM
 Minerals having the same composition but different chemical structures
 Ex. Pyrite and marcasite (FeS2), calcite and aragonite (CaCO3), diamond and graphite (C)
ALIASES / A.K.A.s
Calcite Quartz Pyrite Olivine Uranite Adularia -
Iceland spar
Ice crystal
Fool’s gold
Peridot
Pitchblende
Moonstone
OPTICAL PROPERTIES
 Pattern of reflected x-rays
 Double refraction
o Ability to split a beam into two
o Ex. Calcite
PHYSICAL PROPERTIES
 Crystal form
o General outward appearance
o Groups of crystal faces which display the same physical and chemical properties due to
similarity in arrangements
o Law of constancy of interfacial angles
 Angles between equivalent faces of crystals of the same substance, meausured at the
same temperature, are constant
o Ex. Prismatic, cubic
 Crystal habit
o External shape
o Ex. Botryoidal, fibrous, granular
 Color (least diagnostic property, impurity)
o Idiochromatic
 Inherent, unchangeable mineral color
 All minerals in the same group have the same color
 Ex. Muscovite (colorless), azurite (blue), sulfur (yellow)
o Allochromatic
 Minerals with exotic variety of colors
 Ex. Quartz – amethyst (purple), citrine (yellow)
Corundum – ruby (red), sapphire (blue), emery (black, grey)
 Luster
o Quality and intensity of light reflected from mineral
o Groups:
 Metallic – luster of untarnished metal
 Dark/opaque minerals (ex. Pyrite, gold)
 Non-metallic – usually colored minerals
Resinous – like resin
Adamantine – diamond
Greasy – covered in oil
Vitreous – glassy
Silky – silk-like
Earthy – dull
Pearly – pearl-like
 Streak
o Color of powdered/pulverized mineral
o Most common = white
o Ex. Hematite – reddish color, black streak; limonite – brown color, yellow streak
 Hardness
o Ability of a mineral to withstand abrasion or scratching
o Moh’s Scale of Hardness – True Geologists Can Fry An Old Quail To Certain Degree
1
2
3
4
5
6
7
8
9
10
o
Talc
Gypsum
Calcite
Fluorite
Apatite
Orthoclase
Quartz
Topaz
Corundum
Diamond
Practical scale (kasi kalokohang dalhin ang mga samples ng Moh’s Scale)
2 – 2.5
3
5 – 5.6
6–7
7
Fingernail
Copper coin
Glass plate / knife blade
Steel file
Streak plate
 Cleavage
o Characteristic tendency of minerals to split easily along certain planes
o Governed by internal arrangement, type of bonding, atomic spacing
o Cleavage table:
Number
Quality
Example
1
Perfect
mica
0
2
Very good at 90
feldspar
Fair at 900
pyroxene
Very good at 560/1240
amphibole
3
Cubic (perfect at 900)
halite (salt)
Rhombohedral (perfect at 750)
calcite
4
Perfect
diamond
6
perfect
sphalarite
 Fracture
o Nature of the surface formed by breaking in the direction other than that of cleavage
o Types:
 Conchoidal – chipped off (like glass) Ex. Quartz
 Splintery – fibrous materials, resembles broken plywood
 Irregular – neither conchoidal nor splintery
o Parting
 Breaking along planes of structural weakness
 Result of twinning or pressure
 Specific gravity
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑎 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑚𝑖𝑛𝑒𝑟𝑎𝑙
o SG = 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑎𝑛 𝑒𝑞𝑢𝑎𝑙 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟
Measured by spring-scale/estimation
Quartz
2.65
Ice
0.9
Feldspar
2.56 – 2.76
Gold
19.3
Galena
~7.5
Tenacity
o Resistance of a mineral to breaking, crushing, bending, or tearing
o Types:
 Brittle – breaks/powders easily
 Malleable – can be hammered into thin sheets
 Sectile – can be cut into thin shavings
 Ductile – can be drawn into wire
 Flexible – bends but does not return to original shape
Taste
o Halite(salt) = salty
Smell
o Clay minerals – earthy
o Sulfuric – rotten eggs
Feel
o Talc – soapy
o Graphite – greasy
Magnetism
o Magnetite (lodestone, bato balani)
HCl (Hydrochloric acid) test
o Carbonate – effervescence (fizz)
 Calcite
 Dolomite – no reaction because of Mg, but reaction can be induced in powder due
to increased surface area for CaCO3
Double refraction – Ex. Calcite
Fluorescence
o Re-emission of absorbed light
Striation
o Presence of parallel, hair-like grooves along the surface of mineral
o

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8 MOST ABUNDANT
ELEMENTS (CRUST)
Oxygen
Silicon
Aluminum
Iron
Calcium
Sodium
Potassium
Magnesium
COMMON ROCK-FORMING MINERALS
Quartz (felsic)
Feldspar (felsic)
Feldspathoids
Mica (mafic)
Pyroxene (mafic)
Amphibole (mafic)
Olivine(mafic)
ADDITIONAL TERMS / NOTES:
 Silica tetrahedron – basic building block of crust
 Silicates – most abundant mineral group
 Feldspars – most abundant mineral
 Polymerization – process by which silica tetrahedron molecules share oxygen or metals
 Quartz –conchoidal fracture, 7 hardness
 Feldspar – 2 cleavage planes, 6 hardness
o Plagioclase – grey to white, striation
o K-feldspar – pink
 Olivine – green and granular
 Mica
o Muscovite – light
o Biotite – dark
 Pyroxene – 2 cleavage planes at 900
 Amphibole – 2 cleavage planes at 540/1260
 Granite – light, silicon, aluminum, felsic
 Basalt – dark, silicon, magnesium, mafic
 Acidity/Basicity:
Acidic
Basic
Ultrabasic
High SiO2
Low SiO2
Very low/absent SiO2
Granite
Basalt
Peridotite
/gls07192011
Inspired kasi XD
Credit goes to Jon Tiosin,
kasi majority ng content
galing sa Supernotes
may konting annotations
lang ako, at mga hirit na ewan
kung may mali, sabihan
niyo ako, para ma-edit ko pa