Earth Science: Branches and Key Concepts

• Earth Science includes all sciences that collectively seek to understand Earth and its neighbor in space
• Earth is at the perfect location, also known as the Goldilocks Zone

Four Major Branches of Earth Science

• Geology: Study of the Earth
• Physical Geology studies Earth's materials and the processes that occur below and on its surface
• Minerals of the Earth include lava (after eruption) and magma (before eruption)
• Historical Geology aims to understand the origin of Earth and its development through its history
• Oceanography studies the ocean
• It studies the ocean's physical properties, sea floor topography, chemical composition, ecosystems, and coastal processes
• Oceanography integrates chemistry, biology, physics, and geology
• Meteorology studies the atmosphere and the processes that produce weather and climate
• Weather conditions are experienced in the atmosphere
• Astronomy studies the universe
• Astronomy includes celestial objects such as stars, planets, comets, and galaxies
• It involves understanding their origins, movements, compositions, and the physical laws that govern them
• The universe is studied because of the Big Bang Theory
• Understanding the Earth and its processes means understanding it's a part of a bigger universe

Earth's Spheres

• The atmosphere is the layer of gases surrounding Earth, which includes oxygen, nitrogen, and other gases
• The atmosphere protects the planet, regulates temperature, and enables weather and climate
• The stratosphere is one of the layers in the atmosphere
• The hydrosphere includes all the water on Earth, including oceans, lakes, rivers, groundwater, and ice
• The hydrosphere plays a vital role in supporting life, shaping the land, and regulating climate
• Other planets are not habitable because the water is frozen
• The earliest life forms were found in water forms (bacteria, etc.)
• The geosphere is the solid part of Earth, consisting of rocks, minerals, and the land itself
• It includes the Earth's crust, mantle, and core, and is involved in processes like earthquakes, volcanic activity, and formation of mountains
• A part of the geosphere is the lithosphere
• The physical composition of the Earth (out to in): Crust, Mantle, Core
• The biosphere includes all living organisms on Earth, including plants, animals, and humans, as well as the ecosystems they form
• The biosphere interacts with the other spheres to support life and maintain ecological balance

Nature of Science

• Facts are collected to seek an answer to a well-defined question
• A hypothesis is constructed as a tentative explanation, based on the gathered facts
• A hypothesis is elevated as a theory, which is well tested and widely accepted

Astronomy

• The Big Bang Theory is the most accepted theory of the Origin of the Universe
• "Big Bang" is a mocking name
• The universe began as a single, extremely hot, and dense point around 13.8 billion years ago
• The Big Bang was an expansion, rather than an explosion, of space itself
• Expansion of single identity
• Proponent: George Lemaître
• The hypothesis of the primeval atom or cosmic egg
• The Big Bang Theory became the most accepted theory because it had the most evidence

Evidence of the Big Bang

• Cosmological Redshift: The atmosphere of stars absorbs specific wavelengths of light, which tells us the chemical composition and relative distance
• Galaxies moving away from us shifted to longer (redder) wavelengths
• Edwin Hubble discovered that most galaxies are moving away from us and that their speed is proportional to their distance
• Cosmic Microwave Background Radiation was discovered by Arno Penzias and Robert Wilson by accident and received a Nobel Prize in 1978
• It is left over radiation from the Big Bang and is very cold at 2.725 K
• This "first light" has stretched over billions of years due to the universe's expansion, and it now appears in the microwave part of the EM spectrum

Timeline of the Big Bang

• Planck Epoch (Singularity Epoch): 0 to 10^-43 seconds
• All matter was condensed into a single point and all fundamental forces are unified
• Big Bang: 10^43 seconds
• Inflationary Epoch: 10^-36 to 10^32 seconds
• It was an extremely rapid exponential expansion with extremely high temperatures
• Quark Soup: 10^-32 to 1 second
• Liquid-like material formed out of quarks and gluons, the most basic known building blocks of matter
• Nucleosynthesis: 3 to 20 seconds
• Temperature cools down
• Nucleus containing protons and neutrons (positive charge)
• Protons and neutrons combine through nuclear fusion to form hydrogen, helium, and lithium
• Recombination: 240,000 to 300,000
• Able to form neutral atoms using electrons
• The universe was cold enough for hydrogen and helium to form neutral atoms, allowing light to travel freely and creating the CMBR
• Dark Age: 300,000 to 150 million years
• Lightness period before stare formation
• Dominated by diffuse matter, low energy, and "dark matter"
• Reionization: 150 million to 1 billion years
• Quasars formed, which emitted intense radiation
• The universe is composed of ionized plasma
• Star and Galaxy Formation: 300-500 million years
• Solar System Formation: 300,000 to 150 million years
• Steady State Theory: The universe is in a steady state
• One of the main rivals of the Big Bang Theory
• This theory has already been debunked because of the law of conservation of matter: matter is neither created nor destroyed

Fate of the Universe

• Big Crunch Theory: The expansion of the universe reverses, and the universe collapses
• The universe will stop expanding
• Gravitational contraction would follow, causing all matter to eventually collide and coalesce into the high-energy, high-density state from which the universe began
• Open Universe: The universe expands forever
• If the density of the universe is less than the critical value, about one atom for every cubic meter, it will continue to expand forever
• Multiverse Theory: The universe will expand, but within the universe, there are other universes

The Universe

• The universe is a vast, all-encompassing system of matter, energy, space, and time
• It is believed to have begun 13.8 billion years ago and is constantly expanding ever since
• Cosmology is the study of the universe; its origin, structure, and behavior
• The universe expands at the speed of light

Stellar Evolution

• Stellar birth occurs in nebulae which are interstellar clouds rich in dust and gases
• Trigger: shockwave from a catastrophic explosion or supernova (death of a nearby star)
• Mechanism: gravitational attraction of particles causes the cloud to contract, pulling particles to the center

Stages of Stellar Evolution

• Protostar Stage: Not hot enough to engage in nuclear fusion; not yet a star
• Contraction continues, the core of the developing star heats up to 10 million K and radiates energy in the red wavelength
• Stable Main Sequence Star: Outward pressure balances the inward gravitational force
• Nuclear fusion will occur at this stage
• Stars spend 90% of their life as a hydrogen-burning main sequence star
• The sun is expected to remain a stable main sequence star for another 5 billion years
• Red Giant Stage for some cases supergiants
• Usable hydrogen in the star's inferior is consumed, leaving a helium-rich core
• The white dwarf is the center
• The core contracts since it no longer has gas pressure necessary to support against inward force of gravity
• The core's collapse causes its temperature to rise, expanding the star's outer gaseous shell
• Planetary Nebula is the outer shell of Red Giant
• Variable Stage: Eventually the star's gravitational force stops outward expansion and the two opposing forces, gravity and gas pressure, again achieve balance
• Variable stars alternately expand and contract, and never reach equilibrium
• We often see these as stars whose brightness changes irregularly
• Burnout and Death: Stars exhaust their usable nuclear fuel and collapse in response to their immense gravity
• For low-mass stars: white dwarf
• For medium-mass stars (such as the red giant): planetary nebulae
• For massive stars: supernova

Stellar Remnants

• Remnants can result in a black hole or neutron star
• All stars consume their nuclear fuel and collapse into one of three celestial objects -white dwarfs, neutron stars, or black holes
• White Dwarf: After low- and medium-mass stars consume their remaining fuel, gravity causes them to collapse into white dwarfs
• Contains degenerate matter
• Neutron Stars: Remnants of explosive supernova events
• Electrons are forced to combine with protons in the nucleus to produce neutrons
• Black Holes: Densest objectives in the universe
• Immense surface gravity, even light cannot escape it and formed after a supernova event

H-R Diagrams

• Herzsprung-Russel diagram
• Stars are plotted according to temperature and luminosity
• Values on the left are higher so hotter and white dwarfs
• Nebular Hypothesis/Theory: Bodies of our solar system evolved from an enormous rotating cloud called the solar nebula
• Ex: planetary nebula - remnants of red giant as they become gravitationally attracted
• Solar nebula contains microscopic dust grains and the ejected matter of long-dead stars
• The birth of our solar system, which began as a cloud of dust and gas called a nebula, started to gravitationally collapse
• Outside materials formed a flat rotating accretion disk, which cooled down and condensed into grains
• The nebula contracted into a rotating disk that was heated by the conversion of gravitational energy into thermal energy
• The stellar material contracted to the center, forming the protosun
• Cooling of the nebular cloud caused rocky and metallic material to condense into tiny solid particles
• Repeated collisions caused the dust-size particles to gradually coalesce into asteroid-size bodies called planetesimals
• Within a few million years these bodies accreted into the planets
• MVEM:
  • Composition: soil (rocks),
  • Relatively rocky materials, Terrestrial Planets
  • Merc & Ven - 2 hot for us
• JSUN:
  • Composition: ammonia, methane, cooler, Gaseous Planets, Jovian Planets

How a Solar System is Made

• Solar nebula gravitational collapse/contraction due to Supernova
• Protostar/protosun: Not hot enough for nuclear fusion (gradual contraction), rotate collecting matter, GPE → Thermal Energy, Cooling & condensation
• Accretion disk: Collection of outside materials (continue to collect matter
• Protoplanets: Collisions which lead to protoplanets
• Denser materials condense closer to the sun becomes terrestrial, and rockse are created
• Lighter materials condense far away and become jovian - air
• The planet's proximity to the protosun determines its composition
• Protoplanets within the orbit of Mars are rocky since they are made of materials with high melting temperatures (terrestrial planets)
• Beyond Mars, where it is cooler, protoplanets contain more water, carbon dioxide, ammonia, and methane (Jovian planets, gas giants)

How Life is Possible on Earth

• Prokaryote - ocean
• Asteroid bombardment carried water
• Water became liquid (water vapor) through precipitation of atmospheric gases
• Water vapor came from volcanic eruptions and caused by asteroid bombardment

Formation of the Earth's Layers and the Atmosphere

• Through collisions and gravitational attraction, larger planetesimals merged to form the proto-Earth
• Due to intense heating, Earth became hot enough that iron and nickel began to melt
• Heavy metals sank, forming the dense iron-rich core, produced a magma ocean
• Buoyant masses of molten rock rose about the magma ocean which solidified to form a primitive crust
• This started chemical differentiation which established the Earth's interior: iron rich core, primitive crust, and the mantle
• A Mars-sized body (Theia) collided with the proto-Earth
• The debris from this collision coalesced into the Moon
• Volcanic eruptions released gases, forming an early atmosphere
• Gases trapped in the Earth's interior were released through outgassing and this formed the Earth's primitive atmosphere
• Primitive atmosphere consisted of water vapor, carbon dioxide, and sulfur dioxide, (NO FREE OXYGEN)
• As Earth cooled, water vapor condensed to form clouds, and torrential rains began to fill low-lying areas, which became the oceans- Note: highly acidic rain
• Frequent asteroid and comet impacts added water and organic molecules to the Earth
• Chemical reactions in the oceans and atmosphere set the stage for the emergence of life
• First simple life forms, prokaryotes were formed
• Photosynthesizing bacteria, cyanobacteria, began to release oxygen into the water through photosynthesis

Earth's Materials and Minerals

• In geology, minerals are any naturally occurring inorganic solid that possesses an orderly crystalline structure and can be represented by a chemical formula
• Characteristics of Minerals include naturally occurring, solid substance, orderly crystalline structure, and generally inorganic
• Occuring naturally, meaning those produced in a laboratory or by human intervention are not considered minerals (ex. Cubic zirconia, diamond substitute)
• Solid substance only includes crystalline substances that are solid at temperatures encountered at Earth's surface are considered minerals
• Orderly repetitive packing of atom
• Nonorganic refers to substances that are not derived from living organisms and typically lack C-H bonds (ex. salt)
• Can be represented by a chemical formula (ex. Quartz - SiO2)

Properties of Minerals

• Luster means appearance or quality of light reflected from the surface of a mineral.
• Metallic luster - minerals with appearance of metals, such as a native copper, gold nugget
• Submetallic luster looks somewhat dull or tarnished, as if they have a metallic surface that has been weathered
• Nonmetallic looks generally not shiny or reflective
• Ability to transmit light
• Opaque - no light is transmitted, such as hematite
• Translucent - light but not an image is transmitted
• Melting means rocks melt due to intense heat beneath Earth's surface, forming magma
• Cooling and Crystallization means magma or lava cools and solidifies to form igneous rocks which can happen underground or on the surface
• Extrusive igneous rock is pushed outside & quickly solidify
• Intrusive igneous rock cools slowly underneath the earth
• Weathering, Erosion, and Deposition which breaks down rocks into sediments
• These sediments are transported to new locations where they settle in layers in bodies of water or other low-lying area
• Lithification (Compaction, Cementation) are the processes where over time, layers of sediments are compressed and bind together, forming sedimentary rocks
• Metamorphism are the processes where rocks buried deep within the Earth are subjected to high heat and pressure, transforming them into metamorphic rocks, causing them to change their mineral structure
• Uplift brings rocks to the Earth's surface, exposing them to weathering and erosion, restarting the cycle

Types of Rocks

• Igneous Rocks that form from magma or lava solidifications
• Sedimentary, which forms from sediment compaction
• Metamorphic Forms from transformation of other rocks
• Igneous Rocks formed as magma cools and crystallizes
• Magma is molten rock generated by partial melting of rocks in Earth's mantle and in the lower crust
• Lava is molten rock (magma) that reaches the surface
• Intrusive occur through slow magma cooling
• Extrusive occurs through rapid lava cooling
• Intrusive/Plutonic form when molten rock solidifies beneath the Earth's surface
• Has large or coarse-grained crystals due to slow cooling
• Rough, coarse texture has visible interlocking crystals, bigger crystals
• Textures of Igneous Rocks: Coarse Grained (diorite) (intrusive), Fine Grained (rhyolite) (extrusive), Porphyritic (granite) (intrusive), Glassy (obsidian) (extrusive), Vesicular (pumice) (extrusive)

Felsic Rocks

• They are rich in feldspar and silica and that is light in color rich in oxygen
• Ex are granite
• Mafic is rich in magnesium and iron that is dark in color
• Ex is gabbro
• Intermediate are medium-silica rocks with a mix of light and dark minerals
• Ex is diorite 60% of the Earth's crust is composed of Felsic rocks
• Forms from sediment compaction
• Has a crumbly, layered surface
• They can be Clastic: compacted broken rocks (sandstone)
• Chemical Compacted are dissolved minerals (limestone)
• Organic Compacted are biogenic matter (Coal)
• Weathering that occurs rocks at the Earth's surface are broken down into smaller particles through physical or chemical weathering
• Erosion carries the sediments away from their source by natural agents such as water, wind, ice, or gravity
• Deposition are deposited in layers in environments, such as riverbeds, oceans, when the transporting medium slows down
• Lithification (“turning into rock”) due to the compaction of layers of sediments accumulate and the weight of the overlying layers compresses the deeper layers, reducing pore space and expelling water
• Cementation which Minerals dissolved in water precipitate and bind the sediments together, turning them into solid rock Three Types of Metamorphic rocks: Detrital/Clastic
• Sediments from weathered rocks
• Differentiated based on particle size and shape which occurs in weathered rock
• Conglomerate - rounded
• Breccia - angular
• Sandstone and shale/mudstone
• Features of Sedimentary Rocks involves Stratification Layering of sedimentary rock, which occurs when the conditions of sediment deposition change
• Fossils which may be preserved in sedimentary rocks. Form when organisms are buried in sediment, and over time, their remains are replaced by minerals or preserved in some way

Forms of Chemical Rock

• Chemical Sediment occurs when the ions from dissolved minerals precipitate out of water because of changing concentrations of chemicals, leading to dissolution and evaporation

Description

• Types of Metamorphic Rock is prototlith parent rock or the rock form which it was formed
• Metamorphism is when you change form, which leads to changes in mineralogy, texture, and/or chemical composition, which happens in elevated temperatures and pressures, below the Earth's surface to the upper mantle
• Two types of metamorphism are Low grade metamorphism and High grade metamorphism
• The agents of Metamorphism are Heat and Stress
• Confining Pressure: The forces are equally applied in all directions causing the spaces between mineral grains to close, producing a dense rock
• Differential Stress where some forces are greater in one direction than in others, and the deformation develops the metamorphic rock

Types of Metamorphic Rock

• Foliated: Rocks that exhibit a layered or banded appearance due to the alignment of mineral grains under directed pressure
• Forms under regional metamorphism. Ex. Gneiss coarse-grained, with alternating light and dark mineral bands
• Regional metamorphism is a large-scale type of metamorphism that affects extensive areas, typically associated with mountain-building processes
• Results in High, directed pressure which causes deformation and alignment of minerals
• Earthquakes: Sudden release of energy along fault lines
• Exogenic Processes driven by external forces like wind, water, and gravity. They are powered by the energy of the sun in the water cycle and influences wind patterns
• Examples include Weathering, erosion, deposition

Causes of Weathering

• Process by which rocks, minerals, and soils are broken down into smaller particles or dissolved substances by natural forces
• It is a key step in the rock cycle and significantly influences soil formation, landscape development, and ecosystem dynamics
• Two types of of weathering: Mechanical and Chemical

Biological Factors

• Biological Activity like Plants that grow into cracks, and burrowing animals disrupt rocks, causing them to break as well as Organisms produce acids that chemically break down rocks

Effects of Erosion

• Movement of soil components from one place to another
• Erodes Organisms produce acids that chemically break down rocks
• Water causes materials to move downslope, drives mass wasting, saturation of soil increases mass wasting by reducing friction between particles
• The removal of plant roots helps stabilize slopes, and their removal can lead to increased risk
• Deposition is a process in which sediments, carried by natural agents like water, wind, ice, or gravity, are laid down or settle in a new location
• It plays a major role in creating new landforms and enriching soil in floodplains, making them fertile for agriculture
• Slope mass movement is a movement of a material down a slope, includes landslides, rock-slides, mudslides, and rock falls that cause the slope

Formation of Major Landforms

• It is a natural feature of the Earth's surface that has a distinct shape and structure
• Major types: mountains, hills, plateaus, plains
• Minor types: canyons, valleys, buttes, basins

Types of Surfaces

• Mountains are parts of the Earth's surface with steep slopes and small summit area rising above at least 1000 feet sea level
• Mountains are formed over prolonged periods
• Orogenesis is a process of mountain formation, typically as a result of the collision and interaction of tectonic plates
• Key processes collision: of plates; subduction zones; faulting; volcanism
• A fold is formed by the uplift of mainly the folded sedimentary rock strata under compressional forces
• Mountains are created at convergent plate boundaries, sometimes called continental collision zones or compression zones
• Anticlines and synclines are most common up and down folds that result from compression
• They help determine the age of the rock

Natural Rock Formation

• Dome Mountains form when molten rock pushes the Earth's crust upward but does not break through to the surface
• Plains are broad, flat, or gently rolling areas of land
• Erosion describes the long-term leveling of landscapes by weathering and erosion
• Structural Plains is the formations caused by the uplift or subsidence of large land areas without significant folding or faulting
• Rivers contribute to deposition settlement of eroded sediment
• Elevated landforms with a rounded top are recognized as hills

Processes That Shape Valleys

• Valleys are low areas between mountains or hills and are by river waterways. When river erosion is responsible for development, the effect is often the formation glacial valleys