Earth and Life Science – Comprehensive Review

A set of question-and-answer flashcards covering key concepts from the Earth and Life Science reviewer, including Earth systems, internal structure, minerals, rocks, stratigraphy, fossils, plate tectonics, and earthquakes.

What are the four main disciplines of Earth science?

Geology, meteorology, oceanography, and astronomy

According to NASA, how old is Earth?

About 4.543 billion years

Which Earth sphere is a collective layer of gases that envelops the planet?

The atmosphere

List three life-supporting functions of the atmosphere.

Blocks harmful UV radiation, traps heat to warm the surface, and supplies essential gases

What percentage of Earth’s surface is covered by the hydrosphere?

Approximately 71 %

Roughly what fraction of the hydrosphere is saline water?

About 97.4 %

What narrow surface zone hosts all living organisms?

The biosphere

Which sphere extends from Earth’s surface to its center and includes internal and external processes?

The geosphere

What everyday material represents the interface of all four spheres?

Soil

Name Earth’s three compositional layers in order from surface to center.

Crust, mantle, core

Which crust is thicker and less dense, continental or oceanic?

Continental crust

Average density of continental crust vs. oceanic crust?

Continental ≈ 2.7 g/cm³; oceanic ≈ 3.0 g/cm³

What is the boundary between crust and mantle called?

The Mohorovičić discontinuity (Moho)

Which layer makes up more than 80 % of Earth’s volume?

The mantle

Of what alloy is Earth’s core primarily composed?

Iron-nickel (Fe-Ni) alloy

Which physical layer includes all of the crust plus the rigid uppermost mantle?

The lithosphere

Why is the asthenosphere mechanically weak?

High temperature and pressure make peridotite ductile, allowing it to flow slowly

Which mechanical layer is liquid and generates Earth’s magnetic field?

The outer core

Despite high temperatures, why is the inner core solid?

Extreme pressure keeps the iron-rich core in a solid state

List the five criteria that define a substance as a mineral.

Naturally occurring, inorganic, solid, definite chemical composition, ordered crystalline structure

Which property measures a mineral’s resistance to scratching?

Hardness (Mohs scale)

What is mineral cleavage?

Tendency to break along planes of weakness

Specific gravity compares a mineral’s weight to the weight of an equal volume of what substance?

Water

Effervescence in minerals is a reaction with which common acid?

Hydrochloric acid (HCl)

Which two elements form the basic building block of the most abundant mineral group, the silicates?

Oxygen and silicon

How do intrusive and extrusive igneous rocks mainly differ?

Intrusive have coarse crystals (slow cooling); extrusive have fine crystals (rapid cooling)

What loose material compacts to form sedimentary rocks?

Sediments

Clastic sedimentary rocks are classified chiefly by what clast features?

Size, shape (angularity/roundedness), and sorting

What term describes the planar alignment of minerals in metamorphic rock?

Foliation

State Steno’s Law of Superposition.

In an undisturbed sequence, older layers lie beneath younger layers

What principle says strata extend sideways until they thin or meet a barrier?

Law of Lateral Continuity

Which stratigraphic principle deals with igneous intrusions cutting older rocks?

Law of Cross-cutting Relationships

What principle allows correlation of rock layers by fossil content?

Principle of Faunal Succession

Name the three main types of unconformities.

Disconformity, nonconformity, angular unconformity

Define half-life in radiometric dating.

Time required for half of a radioactive parent isotope to decay to its daughter product

State the two key conditions that favor fossil preservation.

Possession of hard parts and rapid burial

Which fossilization method fills pore spaces with minerals from groundwater?

Permineralization

What is the name of Earth’s most recent supercontinent proposed by Wegener?

Pangaea

List four lines of evidence Wegener used for continental drift.

Continental fit (jigsaw), matching fossils, similar rock structures, and paleoclimate indicators

Seafloor spreading occurs along what global feature?

Mid-ocean ridge (oceanic ridge system)

Name any three of the seven major tectonic plates.

E.g., Pacific, North American, Eurasian, African, Antarctic, South American, Indo-Australian

What is created at a divergent plate boundary?

New lithospheric crust

Give a modern example of continental rifting.

East African Rift (including the Red Sea)

What is a subduction zone?

Region where one tectonic plate descends beneath another

Deep-ocean trenches are associated with which plate interaction?

Oceanic-continental or oceanic-oceanic subduction at convergent boundaries

Volcanic island arcs form at what type of plate convergence?

Oceanic-oceanic convergence

Mountain-building due to continental collision is called what?

Orogeny

Which plate boundary type involves plates sliding past each other without creating or destroying crust?

Transform boundary

Point on Earth’s surface directly above an earthquake focus is called?

Epicenter

Name the two categories of seismic body waves.

Primary (P) waves and Secondary (S) waves

Through which states of matter can P waves travel?

Solids, liquids, and gases

Why can’t S waves pass through Earth’s outer core?

They cannot propagate through liquids

Which surface wave causes ground to move in a rolling, ocean-like motion?

Rayleigh wave

Which magnitude scale is preferred today for large earthquakes (M ≥ 5)?

Moment Magnitude Scale (Mw)

Around what tectonic zone do roughly 81 % of global earthquakes occur?

Circum-Pacific Belt (Ring of Fire)

Describe block motion in a normal fault.

Hanging wall moves downward relative to the footwall