Science Fundamentals: Rocks, Minerals, Plate Tectonics & More

Posted on Mar 6, 2025 in Geology

Science Overview

What is Science?

  • Derived from Latin scientia, meaning knowledge.
  • Discovery through observation; not static, continuously evolving.
  • Creation of new knowledge through research.

Types of Knowledge:

  • Belief Knowledge: Inherent, personal, and often supernatural.
  • Research Knowledge: Universal, based on observable and measurable phenomena.

Facts:

  • Derived from both belief and research knowledge.
  • Science is based on facts that can be tested and repeated.

How Science Works:

  • A process of observations (data), interpretations (hypotheses), and iteration.
  • Peer review is essential to validate findings.

Good Science:

  • Encourages doubt and questioning of established ideas.
  • Recognizes bias in observations.
  • Accepts multiple explanations for an observation.

Pseudoscience:

  • Uses scientific language but lacks scientific rigor.
  • Avoids falsification and peer review.


Rocks and Minerals

What is a Rock?

  • An aggregate of minerals or mineraloids.

Minerals:

  • Naturally occurring, inorganic solids with an orderly internal structure and definite chemical composition.
  • Common minerals:
    • Silicates: Quartz (SiO2), Feldspar (KAlSi3O8)
    • Carbonates: Calcite (CaCO3, forms limestone)
    • Oxides: Hematite (Fe2O3)
    • Halides: Halite (NaCl, table salt)
    • Sulfides: Pyrite (FeS2, “fool’s gold”)

Earth’s Composition:

  • Whole Earth: Iron (32%), Oxygen (30%), Silicon (15%), Magnesium (14%), Sulfur (3%).
  • Crust: Oxygen (47%), Silicon (28%), Aluminum (8%), Iron (5%), Calcium (4%), Sodium (3%), Potassium (2.5%), Magnesium (2%).


Types of Rocks:

  • Igneous: Formed from cooling magma or lava.
    • Intrusive: Cools slowly underground (e.g., granite).
    • Extrusive: Cools quickly on the surface (e.g., basalt, obsidian).
  • Sedimentary: Formed from weathered rock fragments.
    • Clastic: Made of rock fragments cemented together (e.g., sandstone, shale).
    • Chemical: Precipitated from solutions (e.g., limestone).
  • Metamorphic: Formed under heat and pressure without melting.
    • Foliated: Minerals aligned under pressure (e.g., schist, gneiss).
    • Non-Foliated: No alignment of minerals (e.g., marble, quartzite).

The Rock Cycle:

  • Continuous transformation driven by geologic processes.


Plate Tectonics

Theory:

  • Earth’s outer shell is divided into plates that move.

Plate Boundaries:

  • Divergent: Plates move apart (e.g., mid-ocean ridges).
  • Convergent: Plates collide (e.g., subduction zones, Himalayas).
  • Transform: Plates slide past each other (e.g., San Andreas Fault).

Evidence for Plate Tectonics:

  • Fossil distribution (e.g., Mesosaurus found in South America and Africa).
  • Mid-ocean ridges & magnetic stripes confirm seafloor spreading.
  • Deep earthquakes occur along subduction zones.


Geologic Time

Principles:

  • Superposition: Older layers are at the bottom.
  • Original Horizontality: Layers form horizontally.
  • Cross-cutting relationships: A feature cutting another is younger.

Dating Methods:

  • Relative Dating: Determines sequence without exact dates.
  • Absolute Dating: Uses radiometric dating for numerical ages.

Geologic Time Scale:

  • Precambrian (87% of Earth’s history): Earliest life forms.
  • Phanerozoic Eon: Defined by fossil succession.


Fossils & Evolution

Types of Fossils:

  • Body Fossils: Physical remains (bones, shells).
  • Trace Fossils: Evidence of activity (footprints, burrows).
  • Chemical Fossils: Chemical traces indicating past life.

Fossilization Process:

  • Hard parts and low-energy environments increase preservation likelihood.
  • Taphonomy: Study of processes between death and fossilization.

Evolutionary Biology:

  • Taxonomy: Classification of organisms.
  • Phylogeny: Evolutionary relationships, represented as trees.
  • Cladistics: Uses parsimony to infer relationships.
  • Natural Selection: Traits improving survival are favored.


DNA & Evolution

DNA Structure:

  • Double-helix with nucleotide base pairs (A-T, C-G).
  • Stores genetic information.

Central Dogma of Biology:

  • Replication: DNA copies itself (enzyme: DNA polymerase).
  • Transcription: DNA → mRNA (enzyme: RNA polymerase).
  • Translation: mRNA → Protein (performed by ribosomes).

Mutation & Evolution:

  • Mutations introduce genetic variation.
  • DNA comparisons reveal evolutionary relationships.
  • Molecular phylogeny compares sequences to determine relatedness.