Eduqas GCSE Geology · 3.1

Planetary Geology

50 revision questions with answers for 3.1 Planetary Geology in Eduqas GCSE Geology (spec C480QS). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, Five Degrees, Associations, or read every question and answer below. Not official Eduqas material.

All 50 questions and answers

Question 1
What is planetary geology?
Answer:
The study of geological materials, landforms and processes on planets and other Solar System bodies.
Question 2
What is a geological analogue?
Answer:
A familiar example used to help interpret a similar feature or process elsewhere.
Question 3
How can uniformitarianism help in planetary geology?
Answer:
Processes observed on Earth help suggest how similar landforms developed on other bodies, while conditions may differ.
Question 4
Why must Earth analogues be used cautiously for Mars?
Answer:
Mars has different gravity, atmosphere and temperature, so similar features may form differently.
Question 5
Give two planetary properties that can influence geological processes.
Answer:
Gravity and atmospheric pressure; temperature, atmosphere and rock type also matter.
Question 6
How can lower gravity affect a volcanic landscape?
Answer:
It can influence eruption dynamics and the size or shape of landforms, alongside other factors.
Question 7
Why is Earth's surface generally more actively recycled than the Moon's?
Answer:
Earth has active plate tectonics, atmosphere and liquid water that deform, erode and replace surface rocks.
Question 8
Why are many lunar craters well preserved?
Answer:
The Moon has little atmosphere or surface liquid water, so weathering and erosion are limited.
Question 9
How do atmospheric differences affect surface weathering?
Answer:
Atmospheric gases, pressure and water availability influence chemical and physical weathering processes.
Question 10
Why do remote observations alone not always establish a rock's exact origin?
Answer:
Different processes can produce similar appearances; composition and geological context provide additional tests.
Question 11
What is a meteorite?
Answer:
A fragment of extraterrestrial material that survives passage through the atmosphere and reaches the ground.
Question 12
How can meteorites inform ideas about Earth's composition?
Answer:
Their materials provide clues about the components of the early Solar System and possible Earth interior composition.
Question 13
Why are iron-rich meteorites useful analogues for part of Earth?
Answer:
They provide evidence for metal-rich material, useful when considering the composition of Earth's core.
Question 14
Why are stony meteorites useful for Earth science?
Answer:
Their silicate minerals provide evidence about rocky Solar System material and mantle-like compositions.
Question 15
Can one meteorite be assumed to represent every layer of Earth?
Answer:
No. Meteorites vary in composition, and Earth has differentiated into distinct layers.
Question 16
What produces an impact crater?
Answer:
A high-speed collision excavates and deforms a planetary surface.
Question 17
Name a common shape of an impact crater viewed from above.
Answer:
Approximately circular, although later modification may change the shape.
Question 18
What is ejecta?
Answer:
Material thrown out from an impact crater during excavation.
Question 19
Why can larger impacts have global effects on a planet's biosphere?
Answer:
Dust, aerosols and fires can alter climate and reduce sunlight over large areas.
Question 20
How could impact evidence be used in a geological history?
Answer:
A crater cuts or overlies older terrain and can itself be cut or buried by younger features.
Question 21
Two equally preserved surfaces have different crater densities. Which is likely to be older?
Answer:
The more heavily cratered surface is often older, if impact rates and resurfacing are comparable.
Question 22
Why is crater counting an estimate rather than a perfect clock?
Answer:
Impact rates and later resurfacing vary, and small craters can be hidden or erased.
Question 23
How can the Moon help us understand impact processes on Earth?
Answer:
Its preserved craters display impact structures that erosion and tectonics may have erased on Earth.
Question 24
A crater has a diameter of 10 km. Estimate its circumference using pi = 3.14.
Answer:
Circumference = pi x diameter = 31.4 km.
Question 25
A crater is 6 cm across on an image where 1 cm represents 4 km. Calculate its diameter.
Answer:
6 x 4 = 24 km.
Question 26
A circular crater has a radius of 3 km. Estimate its area using pi = 3.14.
Answer:
Area = pi x radius squared = 3.14 x 9 = 28.26 km^2.
Question 27
What evidence might suggest that water flowed on Mars in the past?
Answer:
Channels, rounded sediment and delta-like deposits can be consistent with flowing water.
Question 28
Why do rounded pebbles in a Martian conglomerate suggest transport?
Answer:
Repeated movement and collisions can abrade the clasts, as observed in terrestrial rivers.
Question 29
Are rounded clasts alone conclusive proof of a Martian river?
Answer:
No. Other transport processes can round grains; combine texture with landforms and deposits.
Question 30
What could polygonal cracks on Mars suggest?
Answer:
Drying and shrinkage of wet sediment is one possible explanation; other fracture processes must be considered.
Question 31
How might a Martian delta form?
Answer:
Flowing water enters a standing body of water, slows and deposits sediment.
Question 32
What can cross-bedded Martian sediment suggest?
Answer:
Past movement of sediment by wind or water; other evidence is needed to choose between them.
Question 33
Why can large Martian volcanoes persist as surface features?
Answer:
Long-lived volcanic activity and limited plate recycling can allow large edifices to accumulate.
Question 34
How can a chain of small craters superimposed on a channel help date it?
Answer:
The craters are generally younger than the channel surface they cut or overlie.
Question 35
Why can a dry channel on Mars be evidence for past rather than current water?
Answer:
A former flow can carve a landform that remains after the water has disappeared.
Question 36
What does haematite in a red rock indicate about its appearance?
Answer:
Haematite can contribute a reddish-brown colour; its presence alone does not prove a single environment.
Question 37
Why is a scale bar important on a planetary image?
Answer:
It converts image measurements into real dimensions and helps compare the size of features.
Question 38
A feature is 12 mm long; a 5 mm scale bar represents 2 m. Calculate its length.
Answer:
12 / 5 x 2 = 4.8 m.
Question 39
Why compare images taken at different wavelengths or by different instruments?
Answer:
Different measurements can reveal surface composition or structures not obvious in visible light alone.
Question 40
What should an annotated planetary sketch include?
Answer:
The relevant landform outlines, clear labels, scale and orientation if known.
Question 41
How does a geological map help interpret a planetary surface?
Answer:
It shows the distribution and relationships of mapped rock or landform units.
Question 42
A lava flow covers part of a crater rim. Which feature is younger?
Answer:
The lava flow is younger than the part of the crater it overlies.
Question 43
A channel cuts a crater rim and sediment fills the crater. What sequence is suggested?
Answer:
The crater formed first; the channel later cut the rim and transported sediment into the crater.
Question 44
Why should a geological history be given in chronological order?
Answer:
The order connects evidence such as superposition and cross-cutting to a coherent sequence of events.
Question 45
What is one limitation of an overhead image when interpreting subsurface geology?
Answer:
It shows the surface and may not reveal the depth, internal structure or buried relationships directly.
Question 46
How can rover observations complement orbital images?
Answer:
A rover can examine local textures and composition in detail, while orbital images show wider context.
Question 47
A 4 km line is shown by 2 cm on an image. What is the scale in km per cm?
Answer:
4 / 2 = 2 km per cm.
Question 48
How can erosion affect the apparent age of a planetary surface?
Answer:
It can remove older craters and expose younger-looking surfaces, complicating crater-based age estimates.
Question 49
Why is a geological interpretation described as a hypothesis?
Answer:
It is an evidence-based explanation that can be tested or revised using further observations.
Question 50
Why should a comparison of Earth and Mars mention both planets?
Answer:
A complete comparison states the relevant feature or condition on each, rather than describing only one.

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