EARTH SCIENCE

SESSION 3 - UPCAT REVIEW 2018

EARTH SCIENCE

  • Defined as the branch of science that deals with the physical constitution of the Earth and its atmosphere.
  • Can also be viewed as the study of the Earth and its neighbors in space.

BRANCHES OF EARTH SCIENCE

  • Geology:
    • Concerned with the composition of Earth materials, structures, processes, and Earth's organisms, examining how it has changed over time.
  • Meteorology:
    • Studies the atmosphere and how its processes determine weather and climate.
  • Oceanography:
    • Examines oceans and their composition, processes, and the organisms that inhabit them.
  • Astronomy:
    • Focuses on the universe and heavenly bodies, studying other planets to gain insights into Earth.

THE UNIVERSE

  • Big Bang Theory:
    • Proposes that the universe started from a very hot and dense sphere that expanded and condensed into galaxies.
    • The age of the universe is estimated to be 13.8 billion years.
    • Source: krishna.org
  • Nebular Hypothesis:
    • Suggests the solar system formed from a nebula composed of dust and gas.
    • Source: Tarbuck et al. (2012)

SOLAR SYSTEM

  • Located in the Milky Way Galaxy.
  • Comprises:
    • The Sun
    • Planets
    • Moons:
    • Natural satellites orbiting planets; vary in composition.
    • Comets:
    • Cosmic snowballs made of frozen gases, rock, and dust; display a visible tail when near the Sun.
    • Asteroids:
    • Rocky or metallic objects revolving around the Sun; too small to be classified as planets.
    • Meteoroid:
    • A small particle from a comet or asteroid; if it survives atmospheric entry, it's called a meteorite.

PLANETS

  • A planet is defined as an astronomical object that:
    • Orbits the Sun.
    • Has sufficient gravity to maintain a spherical shape.
    • Has cleared the neighborhood of its orbit.
  • Classification of Planets:
    • Terrestrial Planets:
    • Composed mainly of solid rock (e.g., Mercury, Venus, Earth, Mars).
    • Gas Giants:
    • Features thick outer gaseous layers, possibly with small rocky cores (e.g., Jupiter, Saturn, Uranus, Neptune).

THE EARTH

  • Third planet from the Sun, situated between the Sun and the asteroid belt.
  • Shape: Oblate spheroid (bulging at the equator).
  • Completes one revolution around the Sun every 365.25 days.
  • Hosts one natural satellite: the Moon.
  • Solar Eclipse:
    • Occurs when the moon blocks sunlight from reaching Earth.
  • Lunar Eclipse:
    • Occurs when Earth blocks sunlight from reaching the Moon.
  • Tides:
    • Rise and fall of water levels caused by the gravitational pull of the Moon and the Sun.

THE ATMOSPHERE

  • Defined as the layer of gases surrounding the Earth.
  • Composition:
    • Nitrogen: 78.08%
    • Oxygen: 20.95%
    • Argon: 0.93%
    • Neon, Helium, Krypton: 0.0001%

LAYERS OF THE ATMOSPHERE

  1. Troposphere:
    • Closest to Earth’s surface; contains 75% of the atmosphere’s mass; where weather occurs; contains the jet stream.
  2. Stratosphere:
    • Temperature increases with altitude; includes the ozone layer that absorbs ultraviolet radiation.
  3. Mesosphere:
    • Cold layer where temperature decreases with altitude; most meteors burn up in this layer.
  4. Thermosphere:
    • Temperature can reach up to 1500 °C; cloudless and free of water vapor; where auroras occur.
  5. Exosphere:
    • Outermost layer; contains most of Earth’s satellites.

WEATHER

  • Refers to day-to-day atmospheric changes, primarily caused by pressure differences between locations.
  • Weather phenomena include:
    • Rain, wind, hail, snow, droughts, tornadoes.

CLIMATE

  • Refers to average weather patterns in a specific area over many years.
  • Types of Climate:
    • Polar, Temperate, Tropical.
  • Influenced by factors such as:
    • Topography, wind patterns, altitude.

GREENHOUSE EFFECT

  • The process of trapping heat within the atmosphere.
  • Essential for life but has become excessive due to human activities such as burning fossil fuels and deforestation.

WINDS

  • Created by uneven heat distribution on Earth’s surface.
  • Winds flow from areas of high pressure to areas of low pressure.
  • Coriolis Effect:
    • The deflection of atmospheric movement caused by Earth’s rotation.

ROCKS AND MINERALS

  • Mineral:
    • Naturally occurring inorganic solid substance with a definite composition and structure; the building blocks of rocks.
    • Examples: Quartz, Feldspar, Mica, Pyrite.
  • Properties of Minerals:
    • Color, Streak, Hardness, Luster, Cleavage.

CLASSIFICATION OF ROCKS

  • Rock:
    • A naturally occurring aggregate of minerals; can consist of a single type or multiple types.
  • Classified based on formation processes:
IGNEOUS ROCKS
  • Formed from cooling and solidification of magma:
    • Intrusive Igneous Rocks: Solidified below Earth’s surface; larger crystals and coarser texture (e.g., diorite, gabbro, granite).
    • Extrusive Igneous Rocks: Solidified above Earth’s surface; small or no crystals, resulting in fine-grained or glassy texture (e.g., andesite, basalt, obsidian, pumice, rhyolite).
METAMORPHIC ROCKS
  • Formed by alteration of any rock due to heat, pressure, or chemical action:
    • Foliated: Appears banded due to directional pressure (e.g., gneiss, schist, slate).
    • Nonfoliated: Lacks bands; has a more granular texture (e.g., marble, quartzite).
SEDIMENTARY ROCKS
  • Formed from the accumulation of sediments:
    • Clastic: Composed of fragments of other rocks that cemented together.
    • Biochemical: Created when organisms use dissolved materials to build tissues.
    • Chemical: Formed when dissolved materials precipitate from solution due to supersaturation.

WEATHERING AND EROSION

  • Weathering:
    • The process that breaks down rocks chemically and physically via water, air, and living organisms.
    • Mechanical Weathering: No chemical change; e.g., frost wedging, pressure release.
    • Chemical Weathering: Composition of rocks changes, often facilitated by water; e.g., hydration, oxidation.
  • Erosion:
    • The transportation of material from one location to another; most significant in steep areas.
    • Agents of erosion include: water, wind, ice, waves, gravity.
  • Deposition:
    • The process where materials settle at a location; prominent in low-relief areas like deltas and beaches.

THE EARTH'S COMPOSITION

  • Earth consists of three main layers:
    • Crust:
    • Rocky and brittle; home to tectonic plates.
    • Mantle:
    • Rocky and plastic.
    • Core:
    • Outer Core: Liquid, primarily iron and nickel.
    • Inner Core: Solid, primarily iron and nickel.
CRUST
  • The outer layer, constantly moving due to mantle convection currents:
    • Continental Crust: Thick, old, less dense, primarily granite-like rocks.
    • Oceanic Crust: Thin, young, denser, primarily basalt-like rocks.
MANTLE
  • Second layer, making up 84% of Earth:
    • Contains the asthenosphere, a hot and plastic layer that contributes to convection currents.
CORE
  • Divided by the Gutenberg discontinuity into:
    • Outer Core: Liquid, primarily responsible for Earth’s magnetic field.
    • Inner Core: Solid ball of iron-nickel alloy; solid due to P-waves passing through but not S-waves.

VOLCANOES

  • Openings where magma emerges on Earth’s surface; classified into types:
    • Shield Volcanoes: Gentle slopes, composed of fluid lava; circular or oval in map view.
    • Stratovolcanoes (Composite Volcanoes): Steeper slopes with thick lava flows and pyroclastic materials.
    • Cinder Cones: Small cones mainly of ash and scoria; have craters at the top.
    • Lava Domes: Formed from thick lava; circular mound shape that expands from within.

TECTONIC PLATES

  • Composed of lithosphere (approximately 100 km thick) and float on the ductile asthenosphere.
  • Plate boundaries are zones of earthquakes; interiors exhibit fewer earthquakes.
TYPES OF PLATE BOUNDARIES
  1. Divergent: Plates moving apart.
  2. Convergent: Plates collide; oceanic crust, being denser, subducts.
  3. Transform: Plates slide past each other.

EARTHQUAKES

  • Result from the sudden release of stored energy in elastically strained rocks, causing seismic waves.
  • Can be triggered by bomb blasts, volcanic activities, and fault slippages.

FAULTS

  • Classified based on direction of displacement:
    • Types of Faults:
    • Normal: Hanging wall moves down.
    • Reverse: Hanging wall moves up.
    • Thrust: Special reverse fault with a dip of less than 45°.
    • Strike Slip: Horizontal displacement; left-lateral or right-lateral.
    • Oblique Slip: Combination of dip and strike slip.
    • Blind: Do not reach Earth’s surface; rocks above may fold over the fault's tip.

SEISMIC WAVES

  • Emanate from the focus of an earthquake, traveling in various ways:
    • Body Waves: Travel through Earth’s body; includes P-waves and S-waves.
    • P-waves: Primary waves that can move through solids and liquids.
    • S-waves: Secondary waves that can only move through solids and are slower than P-waves.
    • Surface Waves: Travel along paths near the Earth’s surface, do not penetrate deeply.

REFERENCES

  • A variety of sources provided background on topics discussed, including geological references and scientific articles on Earth Science topics.