CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The process by which Earth separated into layers of different density is called:
A. Differentiation
B. Weathering
C. Denudation
D. Sublimation
Correct Answer: A
Planetary differentiation separated Earth into a metallic core, silicate mantle and crust.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Earth's internal differentiation caused dense materials to:
A. Rise to the surface
B. Sink toward the center
C. Remain evenly mixed
D. Move into the atmosphere
Correct Answer: B
Dense metallic materials sank toward the center while lighter silicates rose, producing layered structure.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Primordial heat within the Earth refers to heat remaining from:
A. Modern industry
B. Earth's formation and differentiation
C. Solar flares only
D. Atmospheric friction
Correct Answer: B
Primordial heat is leftover energy from accretion, compression and differentiation during Earth's formation.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
An important present-day source of Earth's internal heat is:
A. Radioactive decay
B. Moonlight
C. Ocean evaporation
D. Photosynthesis
Correct Answer: A
Decay of radioactive isotopes such as uranium, thorium and potassium contributes substantially to Earth's internal heat.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The geothermal gradient:
A. Remains constant all the way to Earth's center
B. Varies with depth and tectonic setting
C. Is zero beneath oceans
D. Depends only on latitude
Correct Answer: B
The geothermal gradient varies by location and is not constant throughout the Earth.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
A typical near-surface continental geothermal gradient is about:
A. 1–2°C per km
B. 5–10°C per km
C. 25–30°C per km
D. 100°C per km
Correct Answer: C
Near the surface, a commonly cited average is around 25–30°C per km, though it varies widely.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The rate of temperature increase with depth near Earth's surface is called the:
A. Geothermal gradient
B. Coriolis gradient
C. Barometric gradient
D. Adiabatic lapse rate
Correct Answer: A
The geothermal gradient describes how temperature rises with depth, especially in the crust.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Temperature inside the Earth generally:
A. Decreases with depth
B. Increases with depth
C. Remains exactly constant
D. Drops to zero at the core
Correct Answer: B
Earth's internal temperature generally increases with depth.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
As depth within the Earth increases, pressure generally:
A. Decreases
B. Remains constant
C. Increases
D. Becomes zero
Correct Answer: C
Pressure rises with depth because of the increasing weight of overlying material.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The inner core was inferred primarily from:
A. Ocean tides
B. Seismic-wave behavior
C. Volcanic gases
D. Atmospheric circulation
Correct Answer: B
Seismic arrivals passing through or reflecting from the inner core revealed its existence.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The discovery of the Earth's inner core is credited to:
A. Alfred Wegener
B. Inge Lehmann
C. Charles Lyell
D. James Hutton
Correct Answer: B
Danish seismologist Inge Lehmann proposed the solid inner core in 1936.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Direct S-waves are generally absent beyond about:
A. 30° from the epicenter
B. 60° from the epicenter
C. 103° from the epicenter
D. 180° only
Correct Answer: C
S-waves do not pass through the liquid outer core, producing an S-wave shadow beyond roughly 103°.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The approximate angular range of the P-wave shadow zone is:
A. 0°–30°
B. 30°–60°
C. 103°–142°
D. 150°–180° only
Correct Answer: C
The classic P-wave shadow zone lies approximately between 103° and 142° from the earthquake focus.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The P-wave shadow zone is mainly produced by:
A. Reflection from mountains
B. Refraction at the core-mantle boundary
C. Absorption by the crust only
D. Atmospheric turbulence
Correct Answer: B
P-waves are strongly refracted when entering the liquid outer core, producing a shadow zone.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Seismic waves change speed at internal boundaries because of changes in:
A. Latitude only
B. Density and elastic properties
C. Day length
D. Atmospheric humidity
Correct Answer: B
Wave velocities depend on the density and elastic properties of the material through which they travel.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
A major reason scientists know about Earth's deep interior is the study of:
A. Cloud types
B. Seismic waves
C. River discharge
D. Soil color
Correct Answer: B
Changes in seismic-wave speed, direction and transmission reveal internal boundaries and physical states.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The failure of S-waves to pass through the outer core indicates that the outer core is:
A. Solid
B. Liquid
C. Gaseous
D. Vacuum
Correct Answer: B
Because S-waves do not travel through liquids, their absence through the outer core is evidence that it is liquid.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
S-waves can travel through:
A. Solids only
B. Liquids only
C. Solids and liquids equally
D. Vacuum only
Correct Answer: A
S-waves are shear waves and cannot propagate through liquids.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
P-waves can travel through:
A. Solids only
B. Liquids only
C. Solids and liquids
D. Vacuum only
Correct Answer: C
P-waves are compressional waves and can pass through solids, liquids and gases.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which seismic waves travel fastest through the Earth?
A. Surface waves
B. S-waves
C. P-waves
D. Love waves
Correct Answer: C
Primary or P-waves are the fastest seismic body waves.