GEOL 1403 Exam 2 Review Notes

GEOL 1403 Exam 2 Review

Exam Format

  • Multiple Choice: 35 questions, 2 points each (70 points total).
  • Short Answer: 6 questions, 5 points each (30 points total).

Chapter 5: Minerals

  • Definition of a Mineral:
    • Understanding the specific criteria that define a mineral (naturally occurring, inorganic, solid, specific chemical composition, crystalline structure).
  • Atomic Bonding:
    • The effect of atomic bonding on mineral properties (e.g., hardness, cleavage).
    • Types of atomic bonds (ionic, covalent, metallic, Van der Waals) and their relative strengths.
  • Mineral Formation:
    • Processes by which minerals form (e.g., crystallization from magma, precipitation from solution, solid-state diffusion, biomineralization, precipitation from a gas).
  • Diagnostic Tools for Mineral Identification (Slide 30):
    • Streak, hardness (Mohs scale), luster, cleavage/fracture, color, specific gravity, crystal habit, etc.
  • Most Abundant Mineral Class:
    • Silicates are the most abundant mineral class.
    • The "building block" of silicate minerals is the silica tetrahedron (SiO_4).

Chapter 6: Igneous Rocks

  • Lava vs. Magma:
    • Lava is molten rock on the Earth's surface; magma is molten rock beneath the surface.
  • Definition of Igneous Rock:
    • Rocks formed from the cooling and solidification of magma or lava.
  • Intrusive vs. Extrusive Igneous Rocks:
    • Intrusive (plutonic) rocks cool slowly beneath the surface, resulting in large crystals.
    • Extrusive (volcanic) rocks cool quickly on the surface, resulting in small crystals or glassy texture.
  • Magma Creation (3 Processes):
    • Decompression melting: decreasing pressure allows melting.
    • Addition of volatiles: lowers the melting temperature of rocks.
    • Heat transfer: rising magma melts crustal rocks.
  • Variation in Melts (Magma) (4 Processes):
    • Source rock composition: different source rocks yield different magmas.
    • Partial melting: produces magma more felsic than the source rock.
    • Assimilation: magma incorporates surrounding rocks.
    • Magma mixing: different magmas blend together.
  • Fractional Crystallization:
    • Process by which different minerals crystallize from magma at different temperatures, changing the magma's composition.
  • Intrusive Igneous Structures:
    • Dikes (vertical intrusions), sills (horizontal intrusions), batholiths (large, irregular intrusions), laccoliths (dome-shaped intrusions).
    • Sketching these structures.
  • Exposure of Intrusive Igneous Rocks:
    • Uplift and erosion of overlying rocks.
  • Classification of Igneous Rocks:
    • Composition (felsic, intermediate, mafic, ultramafic) and texture (coarse-grained, fine-grained, porphyritic, glassy, vesicular).
    • Texture reflects cooling history (slow cooling = large crystals, fast cooling = small crystals or glass).
  • Plate Tectonics and Igneous Rocks:
    • Association between different plate tectonic settings (e.g., mid-ocean ridges, subduction zones, hotspots) and the types of igneous rocks formed.

Interlude B: Weathering and Sediment

  • Sediment Definition:
    • Loose, solid particles originating from the weathering and erosion of rocks, chemical precipitation from solution, or secretion by organisms.
  • Physical vs. Chemical Weathering:
    • Physical weathering: mechanical breakdown of rocks (e.g., frost wedging, abrasion, jointing).
    • Chemical weathering: chemical alteration of rocks (e.g., dissolution, oxidation, hydrolysis).

Chapter 7: Sedimentary Rocks

  • Four Categories of Sedimentary Rocks:
    • Clastic, biochemical, chemical, and organic.
  • Identification of Clastic Sedimentary Rocks:
    • Grain size (gravel, sand, silt, clay).
    • Sorting (well-sorted vs. poorly sorted).
    • Sphericity (roundness of grains).
    • Maturity of the rock reflects transport distance/time.
  • Lithification Process (Slide 10):
    • Compaction and cementation.
  • Biochemical and Chemical Sedimentary Rocks:
    • Formation through chemical precipitation or biological activity (e.g., limestone, chert, evaporites).
  • Organic Sedimentary Rocks:
    • Formed from the accumulation of organic matter (e.g., coal, oil shale).
    • Important deposits found in them (fossil fuels).
  • Sedimentary Structures:
    • Bedding, cross-bedding, ripple marks, mud cracks.
    • Information they provide about past environments (e.g., current direction, depositional environment).
  • Environments of Deposition:
    • Continental (rivers, lakes, deserts, glaciers).
    • Marine (shallow marine, deep marine).
    • Transitional (deltas, beaches, tidal flats).
    • Understanding the types of rocks that form in each environment.