geo 1

science

a way of knowing a natural phenomena

• - based on observation, identification, description and experimental investigation of real materials

• - requires an organized body of knowledge

• - seeks a theoretical explanation for natural phenomena

beginning of science

5000 years ago → 3000 BC

• - earliest scientists where ancient Egyptians

Aristotle

384 BC → 322 BC

• - philosopher in ancient greek

scientific method

1.) way of thinking that is purely philosophical

2.) to establish theoretical explanations and natural laws

Copernican Revolution

1543 → the beginning of the scientific revolution

Science can always tell the truth

false

Geology

• - a science that deals with the history of earth and its life especially as recorded in rocks

• - a study of solid matter in a celestial body

Earth system

1.) Atmosphere

2.) Hydrosphere

3.) Lithosphere

4.) Biosphere

3 big questions for early geologists

1.) how does the earth form

2.) how old is the earth

3.) what is the meaning of fossils

modern geology

• - scientific - evidence based studies

• - seeking answers for 3 questions

• - started in late 18th century

James Hutton

• - 1726-1797

• - founder of modern geology

• - published the theory of earth in 1785

The original meaning of geology refers to the study of

the Earth

Today geologists study only the Earth

false

Two main data sources for learning earth and life histories?

1.) Rocks

2.) Fossils

Numerical data for ‘absolute age’

1.) radiometric → radioactive decay

2.) paleomagnetism

Radioactive decay

• - radioactivity or nuclear decay

• - changing atomic mass (weight) of radioactive elements overtime

Atomic mass number

number of protons + number of neutrons

Paleomagnetism

the study of the record of the Earth’s magnetic field in igneous and some sedimentary rocks.

• - uses ancient magnetic field that has been recorded

Harry H. Hess

• - pioneer of paleomagnetism

• - 1906-1969: US Navy → not a geologist

• - theory of sea floor spreading & sea floor mapping project in 1960s

3 types of stratigraphy → Absolute age

• - numerical data: Chronostrstography

• - radioactive decay and paleomagnetism

• + numerical and global

• - imprecise sometimes inaccurate

1.) 3 types of stratigraphy → Relative age

Rocks → lithostratigraphy

• + abundant

• - identification

2.) 3 types of stratigraphy → Relative age

fossils → biostratigraphy

• + fine data of time

• - not numerical

hadean

• - 1st time period

• - birth of earth → 4.6 billion years ago

• - oceans and lands → early Precambrian

Archean

• - 2nd time period

• - oldest life → 3.8 bya

• - Precambrian middle

Proterozoic

• - 3rd time period

• - early animals 570 Mya

• - late Precambrian

Paleozoic

• - 4th time period

• - age of fishes

Mesozoic

• - 5th time period

• - after mass extinction 252 mya

• - age of dinosaurs

Cenozoic

• - 6th time period

• - age of mammals

What is the best data source for estimating the age of earth?

radiometric dating → nuclear decay

rocks?

The fossil record indicates dinosaurs lived in the Precambrian

false

Radioactive decay can give us data of ‘absolute age’ for the
geologic time scale

true

Rock layers can provide ‘absolute age’ of the rocks.

false

Terrestrial planets

Mercury – Venus – Earth - Mars

Giant planets

Jupitar - Saturn – Uranus – Neptune

watch video on this !!!!!!

Forming planets & the Earth–Moon system

1.) Solar System (4.6 Ba):

2.) Proto sun“nebula” formation

3.) Dust & ice particles and Sun
4.) Stick & collude – planetesismals

5.) Getting bigger

6.) Differentiation - Earth

7.) Blasting 🡪 Moon (4.51 Ba)

8.) Gas

Earth system & sub systems

1.) atmosphere → air and gasses

2.) hydrosphere → ice water clouds

3.) biosphere → organisms and enviornments

4.) lithosphere → earths rocky surface plate

5.) mantle

6.) core

Lithosphere

• - includes the crust and the upper most portion of the
  mantle

• - 100 kilometers thick and has the ability to glide
  over the rest of the upper mantle

• - Key for earthquake, continental drift, mountain building, and volcanoes
  
  

Earth’s Interior Layers → mantle

• - 83% volume of earth

• - several layers

• - mostly dark dense igneous rock

• - lots of iron and magnesium

Earth’s Interior Layers → core

• - solid inner core & liquid outer core

• - iron and small amounts of nickel

Earth’s outer Layers → crust

• - continental → 20-90 km thick + 2.7 g/cm³ + granite & Al & Si + over 4 billion years old + buoyant (floats on mantle) + forms continents and large land masses

• 
  

• - oceanic → 5-10 km thinner+ 3g/cm³ + basalt and gabbro + young only 200 million yrs old + sits on lower mantle + constantly created and destroyed

Earth’s outer Layers → lithosphere

• - solid upper mantle and crust

Earth’s outer Layers → asthenosphere

• - the upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.

Differentiation

Earth became segregated into a series of concentric layers (core, mantle, crust) because dense materials sank and lighter materials rose while the planet was molten.

• - iron and nickel are heavier so they sink to inner core

• - lighter silicates form mantle and crust

Isostacy

the idea that Earth’s crust floats in gravitational balance on the denser, semi‑fluid mantle beneath it.

• - the earth’s crust is buoyant and floats atop mantle

• - heavier crust sinks deeper into asthenosphere

Plate Tectonic Theory

• explains that Earth’s lithosphere is broken into rigid plates that move slowly over the softer asthenosphere beneath them. These plates interact at their boundaries, creating most of Earth’s major geologic activity.

• - plates move over the asthenosphere due to convection resulting in convection cells

Astronomers think the universe started about

13.8 Ba

Which planets consists of solid rocks?

mars

The Moon formed ‘before’ the Earth

false

Differences between oceanic crusts and continental crusts can be
explained by the concept of ‘isostasy”

true

In the Earth system, which layer has the largest amount of
volume?

mantle

Asthenosphere is a part of mantle

true

Differentiation refers to the buoyancy of crusts on the
asthenosphere.

false

Alfred Wegener

• - proposed continental drift hypothesis

• - Pangea

• - 1880-1930

• - meteorologist

• did not know about the mechanism supporting his theory

Wegeners evidence for Pangea

• - matching mountain ranges

• - matching glacial evidence

• - fossils → distributions of fossils of several organisms supported the
  Wegner’s idea that the continents were once joined together.

Three key plates

• - juan de fuca

• - north american

• - pacific

plate tectonics proposed by Wegner

• - lithosphere broken into plates that move across the asthenosphere due to convection cells

• - evidence after Wenger → earthquakes, volcanoes, sea floor spreading, GBS, fossils

convection

the movement of hot material rising and cooler material sinking inside Earth’s mantle. This slow, continuous circulation is one of the main forces that drives plate tectonics.

• - allows for unpaired electrons to bond therefore creating a magnetic field (active field)

convection cells

• - driving force of plate movement

• - the structured circulation loops formed by convection.

• - circulation patterns

What kind(s) of evidence Wegener did NOT have to support his idea of continental drift?

paleomagnestism

What is the mechanism for plate tectonics

convection cells

Wegener’s idea on ‘continental drift’ is generally considered as a ‘theory’.

true

After Wegener publish the book about continental drift, other geologists immediately accepted the idea.

false

Minerals

naturally occurring homogenous inorganic solids that have a definite chemical composition and crystalline structure

• - help to identify rocks

rocks

consist of more than one kind of mineral

• - tell about history

atoms

• - smallest unit of matter that retains the characteristics of an element

• - protons/ neutrons/ electrons

Common chemical elements and compounds in Earth crusts

Silica-rich (silicon + oxygen) minerals, called ‘silicates’

Why chemical compounds matter in minerals?

they reflect the environment in which the minerals were formed and can explain how and where they came about

• some rocks and minerals formed deep unground may not be stable above ground (temp changes, water, air etc.)

The ‘four’ sources of minerals for rocks

1.) cooling magma

2.) solution in water

3.) other organisms

4.) space

igneous rocks

break down from

• weathering, erosion, dissolution (chemical weathering)

They become

• Clastic sediment

• Dissolved ions → chemical sedimentary

sedimentary rocks

• formed by weathering erosion deposition and cementation

• preserve fossils and past environments

metamorphic rocks

form when heat, pressure, and chemical fluids change a rock without melting it.

changes that occur:

• recrystalization

• new minerals form depending on temperature and pressure

• texture→ foliated vs not

• color change

• density/hardness'

• composition changes if ions are added or subtracted

What makes diamond harder than graphite?

crystalline structure

What is the most common type of minerals in the Earth crusts?

silicate

Minerals are generally identical in crystalline structures and what?

chemical compounds

In geology, minerals can contain both organic and inorganic substances.

false

lava

molten rock that has flowed out onto the surface

magma

molten rock beneath the surface → all contain silicon and oxygen (silicate minerals)

Major Types of Magma → felsic/silicic

66-67% silica → light color

• intrusive → granite

• extrusive → rhyolite

Major Types of Magma → intermediate magma

52-66% silica → medium color

• intrusive → diorite

• extrusive → andesite

Major Types of Magma → mafic magma → intrusive igneou

45-52% silicate → medium dark color

• intrusive → gabbro

• extrusive → basalt

Major Types of Magma → ultramafic magma

38-45% silicate → darkest color

• intrusive → peridotite

silica

SiO²

Extrusive igneous rock → volcanic rocks→ Aphanitic rock

• formed by freezing lava above ground → Aphanitic rock

• quickly cools → fine grain → no crystals

• made from lava

Intrusive igneous rock → plutonic rocks → Phaneritic rock

• formed by freezing magma underground → Phaneritic rock

• slow cooling → coarse grain

• made from magma

• composition ranges from felsic (light) to mafic (dark) depending on silicate content

• gabbro → granite

What is the best example for an extrusive rock?

basalt or rhyolite

In igneous rocks, crystal size is mainly controlled by types of
magma.

false cooling speed

The color of igneous rocks (i.e., light to dark) is generally controlled by the amount of silica.

true

Arthur Homes

• - convection

• - 5cm per year

• - 1890-1965

• radioactive technique for age of earth

Galileo Galilei

• - earliest innovator for scientific method

• - 1564-1642

• - renaissance period in Italy

• - created geometrical and military compasses + innovated telescope

changing thru time →

evolution

How does the earth form?

the earth structure

How old is the earth

4.6 billion years old

what is the meaning of fossils?

fossils are direct evidence of life in the past

paleontology

the study of ancient life using fossils - since 1700s

modern geology answers the 3 main questions

true

mineralogy & petrology

study of rocks

volcanology

study of volcaneos

geophysics

deep earth study → earthquakes & crust movement

structure studies

deformation of crust & tectonics

hydrology

studies ground + surface water