Plate Tectonics and Boundaries

Plate Tectonics

• Plate tectonics is a theory that explains the movement of Earth's plates.
• Plates float on the mantle, driven by convection currents from the Earth's core.
• Modern technology allows measurements of plate movement in centimeters per year.
• Plate tectonics explains how Earth's surface changes over time.

Types of Plate Boundaries

• Convergent boundaries: Plates move towards each other.
  • Can cause subduction (one plate sinking under another) or collision.
  • Denser oceanic plates typically subduct under less dense continental plates.
  • Create volcanoes, trenches, islands, and mountains (e.g., Himalayas).
• Divergent boundaries: Plates move apart.
  • Creates new crust and features like mid-ocean ridges or rift valleys (e.g., Mid-Atlantic Ridge).
• Transform boundaries: Plates slide past each other.
  • Creates fault lines (e.g., San Andreas Fault).
  • Earthquakes occur frequently due to pressure buildup.

Landforms

• Landforms are naturally occurring features of Earth's terrain.
• Geomorphologists study landforms to understand Earth's surface transformations.
• Landform types include coasts, islands, peninsulas, bays, mountains, hills, plateaus, valleys, canyons, and plains.
• Ocean basins also have landforms like abyssal plains, seamounts, trenches, and volcanic islands.

Solar System, Galaxies, and the Universe

• The Solar System includes the Sun, planets, moons, asteroids, and other objects bound by gravity.
• A galaxy is a vast collection of gas, dust, stars, and solar systems held together by gravity.
• The Universe encompasses all matter, energy, space, and time.
• Dark matter is an unknown type of matter in the Universe.
• Galaxies can be spiral, elliptical, or irregular in shape.
• The Universe's size constantly increases.

Celestial Bodies

• Planets: Must have enough gravity to be spherical and clear their orbital path. Must orbit a star.

• Moons: Orbit planets, not stars.

• Asteroids: Made of metal, rock, or a combination. Minor planets (planetoids).

• Comets: Small icy bodies of gas, rock, and dust. Typically have gas tails near the sun.

• Meteoroids: Float in space, various material composition.

• Meteors: Heated meteoroids entering Earth's atmosphere (often burn up).

• Meteorites: Meteors that reach the ground.

• Planets are classified as terrestrial (solid surface, metal core - Mercury, Venus, Earth, and Mars) or Jovian (gas giants - Jupiter, Saturn, Uranus, and Neptune).

Stars

• Stars form in stellar nebulas (gas clouds).
• Protostars develop from collapsing clouds of hydrogen.
• Stars enter the main sequence after hydrogen nuclear fusion begins.
• Main sequence duration depends on star mass (10 million to 1 trillion years).
• Low-mass stars become red giants, then planetary nebulae.
• High-mass stars become red supergiants, then supernovae, leaving neutron stars or black holes.

Constellations and Star Clusters

• Constellations are groups of stars appearing close together.
• Star clusters contain physically close, gravitationally bound stars, formed during galaxy formation.

Sun

• The Sun is a medium-sized, yellow star.
• A ball of plasma (superheated ionized gas).
• Formed in a nebula about 4.5 billion years ago.
• Consists of six layers with varying temperatures.
• Nuclear fusion in the core produces heat and light.
• Sunspots are linked to cyclic magnetic field changes.
• The Sun is 93 million miles from Earth and takes sunlight approximately eight minutes to reach Earth.
• The Sun's distance from Earth supports liquid water and possible life.

This quiz covers the theory of plate tectonics and the different types of plate boundaries, including convergent, divergent, and transform boundaries. Learn how these movements shape Earth's surface and create various landforms such as mountains, volcanoes, and ocean ridges.