Earth Systems Science 1-5

Q: Name the seven major themes of Earth Science.

A: Cosmology & Earth’s structure, Plate tectonics, Earth materials, Earth as a dynamic planet, Natural history of Earth, Earth resources, Surface processes.

Q: What is the geocentric model of the universe?

A: The Ptolemaic model, which places Earth at the center of the universe.

Q: Who promoted the heliocentric model of the solar system?

A: Nicolaus Copernicus.

Q: Which scientists provided key evidence supporting the heliocentric model

A: Galileo Galilei, Johannes Kepler, and Sir Isaac Newton.

Q: What is the approximate diameter of the Sun?

A: ~1.4 x 10⁶ km.

Q: What is the temperature of the Sun’s core?

A: ~10 million K.

Q: What is the temperature of the Sun’s surface (photosphere)?

A: ~5800 K.

Q: How is stellar luminosity commonly expressed?

A: Relative to the Sun’s luminosity (L₀ = 1).

Q: What energy process powers stars on the main sequence?

A: Hydrogen fusion.

Q: What holds stars together?

A: Gravity.

Q: Roughly how many stars are in the Milky Way galaxy?

A: More than 300 billion.

Q: What are the three types of planets in our solar system?

A: Terrestrial, gas giants, and ice giants.

Q: Which planets are terrestrial?

A: Mercury, Venus, Earth, Mars.

Q: Which planets are gas giants?

A: Jupiter and Saturn.

Q: Which planets are ice giants?

A: Uranus and Neptune.

Q: What defines the habitable zone of a solar system?

A: The distance from a star where liquid water can exist (0.8–2.5 AU for our Sun).

Q: What is a moon?

A: A rocky satellite orbiting a planet.

Q: Give one example of a volcanically active moon.

A: Io (Jupiter).

Q: Give one example of a moon with possible liquid water beneath ice.

A: Ganymede (Jupiter) or Enceladus (Saturn).

Q: What are asteroids?

A: Small rocky or metallic objects, usually orbiting between Mars and Jupiter.

Q: What are comets composed of?

A: Frozen gases, rock, and dust (“dirty snowballs”).

Q: Where are most comets thought to originate?

A: Kuiper Belt and Oort Cloud.

Q: What is a meteoroid?

A: A small asteroid or fragment floating through space.

Q: What is a meteor?

A: A meteoroid that burns up in Earth’s atmosphere (“shooting star”).

Q: What is a meteorite?

A: A meteoroid that survives passage and strikes Earth’s surface.

Q: What evidence shows the universe is expanding?

A: Redshift of distant galaxies.

Q: What is the Big Bang Theory?

A: The idea that the universe began 13.8 billion years ago from a singularity.

Q: What is stellar nucleosynthesis?

A: Formation of elements inside stars through fusion.

Q: What are the four stages of planet formation?

A: Nebula, protoplanetary disk, rings of planetesimals, solar system.

Q: What is Earth’s radius?

A: 6371 km.

Q: Which layer of Earth is thinnest?

A: The crust.

Q: What is the thickness range of the crust?

A: 7–70 km.

Q: What is the depth of the mantle?

A: To ~2900 km.

Q: What is Earth’s core composed of?

A: Outer core: liquid iron; Inner core: solid iron alloy.

Q: What generates Earth’s magnetic field?

A: Movement of liquid iron in the outer core.

Q: What is the lithosphere?

A: The crust plus rigid upper mantle.

Q: What is the asthenosphere?

A: A “plastic” layer of the mantle that can deform over long timescales.

Q: What is the geothermal gradient?

A: The change in temperature with depth inside Earth.

Q: What are the two main sources of Earth’s internal heat?

A: Primordial heat (accretion and gravitational energy) and radioactive decay.

Q: How thick is oceanic crust compared to continental crust?

A: Oceanic: 7–10 km; Continental: 25–70 km.

Q: What rock type dominates continental crust?

A: Granite.

Q: What rock type dominates oceanic crust?

A: Basalt.

Q: What are the most abundant elements in Earth’s crust?

A: Oxygen, silicon, aluminum, iron, calcium, magnesium, sodium, potassium.

Q: Who proposed the idea of continental drift?

A: Alfred Wegener.

Q: What was the name of the ancient supercontinent?

A: Pangea.

Q: What was the name of the superocean surrounding Pangea?

A: Panthalassa.

Q: What evidence did Wegener cite for Pangea?

A: Matching coastlines, fossil distribution, past glaciations, climate belts, mountain ranges.

Q: What are glacial striations?

A: Scratches in rock made by glaciers, indicating flow direction.

Q: What past climate evidence supports continental drift?

A: Coal deposits (tropical forests), desert belts, coral reefs.

Q: Why can’t fossils of land animals explain continental separation without drift?

A: They could not cross vast oceans.

Q: What mountain ranges support continental drift evidence?

A: The Appalachians (linked to mountains in Europe and Africa).

Q: What is bathymetry?

A: The study of ocean depths using sonar.

Q: What discovery revealed the Mid-Atlantic Ridge?

A: Bathymetric mapping of the seafloor.

Q: How does sediment thickness change with distance from the ridge?

A: Sediments become thicker and older away from the ridge.

Q: What evidence shows the ocean floor is younger than continents?

A: Thin sediment layers compared to Earth’s age.

Q: Where is heat flow highest on the seafloor?

A: At mid-ocean ridges.

Q: What is magnetic declination?

A: The angle between geographic north and magnetic north.

Q: What is magnetic inclination?

A: The angle between magnetic field lines and Earth’s surface.

Q: What does a rock’s magnetic dipole record?

A: The Earth’s magnetic field at the time of the rock’s formation.

Q: What is a paleopole?

A: The inferred position of Earth’s magnetic pole at the time a rock formed.

Q: What do apparent polar-wander paths show?

A: That continents move relative to each other.

Q: What is magnetic polarity reversal?

A: A switch in Earth’s magnetic field direction.

Q: What do magnetic anomalies on the seafloor indicate?

A: Symmetrical stripes recording polarity reversals, evidence of seafloor spreading.

Q: What is seafloor spreading?

A: The process of new ocean crust forming at ridges and moving outward.

Q: What does the term “convection” mean in relation to Earth’s core?

A: Movement of molten iron in the outer core that drives the magnetic field.

Q: What type of meteorites resemble Earth’s mantle?

A: Stony meteorites (chondrites).

Q: What type of meteorites resemble Earth’s core?

A: Iron meteorites.

Q: What is primordial heat?

A: Heat left from Earth’s accretion and differentiation.

Q: Which isotopes mainly produce Earth’s radioactive heat?

A: Uranium, thorium, and potassium isotopes.

Q: What is the thickness of the lithosphere relative to the asthenosphere?

A: Lithosphere is thin and rigid; asthenosphere is thicker and plastic.

Q: What geological feature marks seafloor spreading centers?

A: Mid-ocean ridges.

Q: Why was Wegener’s continental drift hypothesis initially rejected?

A: He could not explain the mechanism of movement.

Q: What later evidence confirmed plate tectonics?

A: Paleomagnetism and seafloor spreading data.

Q: What are tectonic plates?

A: Rigid pieces of lithosphere that move over the asthenosphere.

Q: What is the difference between continental and oceanic lithosphere?

A: Continental is thicker, less dense; oceanic is thinner, denser.

Q: What process recycles oceanic lithosphere?

A: Subduction.

Q: Where do earthquakes and volcanoes often occur?

A: At plate boundaries.

Q: How does mantle convection drive plate tectonics?

A: Hot material rises, cool material sinks, creating circulation.

Q: Why do ridges have high heat flow?

A: Because hot asthenosphere is close to the surface.

Q: How do fossils of Glossopteris and Mesosaurus support Pangea?

A: They are found on continents now separated by oceans.

Q: What is the current scientific view of Earth’s surface dynamics?

A: Plate tectonics explains continental drift and seafloor spreading.

Q: What is the definition of a mineral?

A: A naturally occurring, solid, crystalline material formed by geologic processes with a definable chemical composition.

Q: What are the four requirements for a substance to be considered a mineral?

A: 1. Naturally occurring, 2. Solid and crystalline, 3. Formed by geologic processes, 4. Definable chemical composition.

Q: Why are synthetic compounds not minerals?

A: Because they are man-made; they are called phases or synthetic materials instead.

Q: What distinguishes crystalline from amorphous substances?

A: Crystalline substances have atoms/ions arranged in a regular periodic grid, while amorphous substances (like glass) lack long-range order.

Q: What are biogenic minerals?

A: Minerals formed by organisms, such as shells, skeletons, teeth, and phytoliths in plants.

Q: Can the composition of minerals vary?

A: Yes, many minerals vary within limits, as in solid solutions (e.g., garnet ranging from Fe to Mg or Ca varieties).

Q: Which metals were known and mined since antiquity?

A: Gold (Au), copper (Cu), lead (Pb), zinc (Zn), and tin (Sn).

Q: What is bronze, and what is its composition?

A: An alloy of copper and tin, with tin less than 11% by weight.

Q: What did Hildegard von Bingen contribute to mineralogy?

A: She published De lapidibus, a detailed description of minerals and gemstones.

Q: Who was Georgius Agricola?

A: A German mining engineer and doctor who wrote De re metallica (1556), giving detailed descriptions of minerals.

Q: What did Max von Laue discover in 1912, and why was it important?

A: X-ray diffraction, proving crystals have a periodic atomic arrangement.

Q: What did the Braggs achieve with X-rays?

A: Determined crystal structures, winning the Nobel Prize in 1915.

Q: What is a crystal?

A: A crystalline material bounded by flat surfaces, where the internal periodic arrangement of atoms is reflected in external symmetry and faces.

Q: How does atomic structure influence crystal shape?

A: The type of bonding (cations and anions, network vs. layered structures) dictates external form, hardness, and cleavage patterns.

Q: What controls the physical properties of minerals?

A: The crystal structure and chemical composition, which determine mass, strength, and interaction with light.

Q: How is density (specific gravity) defined for minerals?

A: It is the ratio of a mineral’s mass to the mass of an equal volume of water, influenced by atomic weight and packing of ions.

Q: What is hardness, and how is it measured?

A: Hardness is a mineral’s resistance to scratching, commonly measured on Mohs scale (1 = talc, 10 = diamond).

Q: What is cleavage, and how does it form?

A: Cleavage is the tendency of a mineral to break along planes of weak atomic bonding, reflecting internal lattice structure.

Q: What is luster in mineralogy?

A: The way a mineral reflects light (metallic vs. nonmetallic, e.g., vitreous like quartz, pearly like talc).