Eduqas A-level Geology · T3

Quaternary geology (option)

50 exam-style questions with answers for T3 Quaternary geology (option) in Eduqas A-level Geology (spec A480QS). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below. Not official Eduqas material.

All 50 questions and answers

Question 1 · Spec T3, Key Idea 1 · Quaternary
State the time span of the Quaternary and name its two epochs. [2 marks]
Answer:
The last 2.6 million years (1); the Pleistocene and the Holocene (1).
Question 2 · Spec T3, Key Idea 1 · Glacials and interglacials
Distinguish between a glacial and an interglacial. [2 marks]
Answer:
A glacial is a cold period when ice sheets expand (1); an interglacial is a warm period when ice sheets retreat (1).
Question 3 · Spec T3, Key Idea 1 · Milankovitch cycles
State what Milankovitch cycles change. [1 mark]
Answer:
The amount and distribution of solar radiation (insolation) reaching the Earth through the seasons.
Question 4 · Spec T3, Key Idea 1 · Milankovitch cycles
Describe eccentricity. [2 marks]
Answer:
The change in the shape of the Earth's orbit from nearly circular to more elliptical (1); over a cycle of about 100 000 years (1).
Question 5 · Spec T3, Key Idea 1 · Milankovitch cycles
Explain how changes in axial tilt affect high-latitude climate. [2 marks]
Answer:
Greater tilt makes summers warmer and winters colder (1); warmer high-latitude summers melt more ice (1).
Question 6 · Spec T3, Key Idea 1 · Milankovitch cycles
Describe precession. [2 marks]
Answer:
The wobble of the Earth's axis (1); which changes the season when the Earth is closest to the Sun, over about 23 000 years (1).
Question 7 · Spec T3, Key Idea 1 · Ice sheet growth
Explain why cool northern summers favour ice sheet growth. [2 marks]
Answer:
Less of the winter snow melts in summer (1); so snow builds up year after year to form ice sheets (1).
Question 8 · Spec T3, Key Idea 1 · Milankovitch cycles
State the approximate periods of the three Milankovitch cycles. [3 marks]
Answer:
Eccentricity: about 100 000 years (1); obliquity (tilt): about 41 000 years (1); precession: about 23 000 years (1).
Question 9 · Spec T3, Key Idea 1 · Feedbacks
Explain why orbital changes alone cannot explain the full temperature change of glacial cycles. [2 marks]
Answer:
The changes in insolation are small (1); so feedbacks such as ice-albedo and greenhouse gases amplify them (1).
Question 10 · Spec T3, Key Idea 1 · Ocean circulation
Explain how changes in seaways affect polar climate. [2 marks]
Answer:
Opening or closing seaways redirects ocean currents (1); changing how much warm water reaches the poles (1).
Question 11 · Spec T3, Key Idea 1 · Ocean circulation
Explain how the opening of the Drake Passage cooled Antarctica. [2 marks]
Answer:
It allowed the Antarctic Circumpolar Current to form (1); which isolated Antarctica from warm ocean water (1).
Question 12 · Spec T3, Key Idea 1 · Uplift
State two ways the uplift of the Himalayas may have cooled the climate. [2 marks]
Answer:
It changed atmospheric circulation, including the monsoon (1); and increased chemical weathering of silicate rocks, removing CO₂ (1).
Question 13 · Spec T3, Key Idea 1 · Climate change causes
Explain why long-term cooling cannot be blamed on a single event. [2 marks]
Answer:
Several forcings and feedbacks act together (1); and their timing and size are uncertain (1).
Question 14 · Spec T3, Key Idea 2 · Glacial deposits
Describe the characteristics of till. [2 marks]
Answer:
Unsorted, with a wide range of grain sizes in a clay matrix (1); with angular or striated clasts (1).
Question 15 · Spec T3, Key Idea 2 · Glacial deposits
Distinguish between till and fluvioglacial outwash. [2 marks]
Answer:
Till is deposited directly by ice and is unsorted (1); outwash is deposited by meltwater, so it is sorted and stratified (1).
Question 16 · Spec T3, Key Idea 2 · Erratics
Explain how erratics show the direction of ice movement. [2 marks]
Answer:
An erratic is a boulder of rock different from the local bedrock (1); tracing it to its source shows the direction the ice moved (1).
Question 17 · Spec T3, Key Idea 2 · Striations
Explain how striations help reconstruct ice movement. [2 marks]
Answer:
Rocks in the base of the ice scratch the bedrock (1); so striations show the direction of ice flow (1).
Question 18 · Spec T3, Key Idea 2 · Drumlins
State what a field of drumlins shows. [2 marks]
Answer:
The direction of ice flow, parallel to their long axes (1); the steep blunt end faces up-ice (1).
Question 19 · Spec T3, Key Idea 2 · Moraines
State what a terminal moraine shows. [1 mark]
Answer:
The furthest position reached by the ice front.
Question 20 · Spec T3, Key Idea 2 · Eskers
Explain why eskers are made of sorted, layered sand and gravel. [2 marks]
Answer:
They were deposited by meltwater streams flowing in tunnels in or under the ice (1); and running water sorts and stratifies sediment (1).
Question 21 · Spec T3, Key Idea 2 · Periglacial
Define periglacial. [1 mark]
Answer:
Cold, non-glacial conditions near the edge of ice sheets, with permafrost and frost action.
Question 22 · Spec T3, Key Idea 2 · Periglacial
Explain how head deposits form in periglacial conditions. [2 marks]
Answer:
Freeze-thaw weathering produces angular rock fragments (1); which move downslope by solifluction over frozen ground (1).
Question 23 · Spec T3, Key Idea 2 · Interglacials
State three types of evidence for an interglacial in British deposits. [3 marks]
Answer:
Any three from: pollen of temperate trees (1); warm-climate beetles (1); warm-climate mammals such as hippopotamus (1); soils or peat (1).
Question 24 · Spec T3, Key Idea 2 · Quaternary record
Explain why the Quaternary record on land is incomplete. [2 marks]
Answer:
Each ice advance erodes earlier deposits (1); so only fragments of the record survive (1).
Question 25 · Spec T3, Key Idea 2 · Ocean cores
Explain why ocean cores give a more complete climate record than land sequences. [2 marks]
Answer:
Sediment accumulates continuously on the deep sea floor (1); while land sequences are eroded by later ice advances (1).
Question 26 · Spec T3, Key Idea 2 · Sea level
Explain why sea level falls when ice sheets grow. [2 marks]
Answer:
Water evaporated from the oceans falls as snow (1); and is stored in ice sheets on land (1).
Question 27 · Spec T3, Key Idea 2 · Isostasy
Explain why the land beneath an ice sheet subsides. [2 marks]
Answer:
The weight of the ice depresses the lithosphere (1); displacing the mantle beneath (isostatic depression) (1).
Question 28 · Spec T3, Key Idea 2 · Isostasy
Explain why land continues to rise after an ice sheet melts. [2 marks]
Answer:
The mantle flows back slowly beneath the land (1); so isostatic rebound continues for thousands of years (1).
Question 29 · Spec T3, Key Idea 2 · Isostasy
Calculate the rebound using rebound = ice thickness × ice density ÷ mantle density, with 1100 m, 900 kg/m³ and 3300 kg/m³. [2 marks]
Answer:
1100 × 900 ÷ 3300 (1); = 300 m (1).
Question 30 · Spec T3, Key Idea 2 · Relative sea level
Land rises by 12 m while global sea level rises by 5 m. Calculate the relative sea level change. [1 mark]
Answer:
Relative sea level falls by 7 m.
Question 31 · Spec T3, Key Idea 2 · Raised beaches
State what a raised beach shows. [1 mark]
Answer:
A former shoreline now above present sea level, due to isostatic uplift or a fall in sea level.
Question 32 · Spec T3, Key Idea 2 · Rias
Explain how a drowned river valley forms. [2 marks]
Answer:
A river valley was cut when sea level was lower (1); it was flooded when sea level rose after the ice melted (1).
Question 33 · Spec T3, Key Idea 3 · Oxygen isotopes
Explain why δ¹⁸O in marine carbonate is higher in glacials. [2 marks]
Answer:
Ice sheets store water rich in ¹⁶O, leaving the oceans enriched in ¹⁸O (1); and shells forming in colder water take up more ¹⁸O (1).
Question 34 · Spec T3, Key Idea 3 · Ice cores
State two types of climate information provided by ice cores. [2 marks]
Answer:
Air bubbles preserve past atmospheric composition, such as CO₂ and methane (1); the isotopes in the ice show past temperatures (1).
Question 35 · Spec T3, Key Idea 3 · Ice cores
Explain why oxygen isotopes in ice cores and marine shells change in opposite directions. [2 marks]
Answer:
In ice, colder conditions give lower δ¹⁸O in the snow (1); in marine shells, colder conditions give higher δ¹⁸O (1).
Question 36 · Spec T3, Key Idea 3 · Pollen
State what an increase in tree pollen in a sequence shows. [1 mark]
Answer:
The spread of woodland, suggesting the climate became warmer.
Question 37 · Spec T3, Key Idea 3 · Pollen
Explain why the percentage of one pollen type can fall even if its abundance does not. [2 marks]
Answer:
Percentages depend on the total pollen count (1); so an increase in other types reduces its percentage (1).
Question 38 · Spec T3, Key Idea 3 · Beetles
Explain why fossil beetles are good climate indicators. [2 marks]
Answer:
Many species have narrow temperature tolerances that are known today (1); and they migrate quickly when the climate changes (1).
Question 39 · Spec T3, Key Idea 3 · Mammals
State what a woolly mammoth fossil shows and what it does not prove. [2 marks]
Answer:
It indicates a cold climate (1); but it does not prove that ice covered the site (1).
Question 40 · Spec T3, Key Idea 3 · Human evolution
Explain how climate change may have influenced human evolution. [2 marks]
Answer:
Changing climate altered habitats and food resources (1); favouring adaptability and migration (1).
Question 41 · Spec T3, Key Idea 3 · Human evolution
Explain why a link in time between climate and human change does not prove cause. [2 marks]
Answer:
Dating uncertainties and incomplete fossils may create a false link (1); a mechanism and other evidence are needed (1).
Question 42 · Spec T3, Key Idea 3 · Radiocarbon dating
Explain how radiocarbon dating works. [2 marks]
Answer:
Living organisms take in carbon-14 while alive (1); after death the carbon-14 decays at a known rate (1).
Question 43 · Spec T3, Key Idea 3 · Radiocarbon dating
A sample retains 12.5% of its carbon-14. Calculate its age using a half-life of 5730 years. [2 marks]
Answer:
12.5% = three half-lives (1); 3 × 5730 = 17 190 years (1).
Question 44 · Spec T3, Key Idea 3 · Radiocarbon dating
Explain why radiocarbon dating cannot date rocks millions of years old. [1 mark]
Answer:
After about 50 000 years too little carbon-14 remains to measure.
Question 45 · Spec T3, Key Idea 3 · Radiocarbon dating
Explain how contamination with modern carbon affects a radiocarbon date. [1 mark]
Answer:
It adds carbon-14, making the sample appear too young.
Question 46 · Spec T3, Key Idea 3 · Radiocarbon dating
Explain why radiocarbon dates must be calibrated. [2 marks]
Answer:
The amount of carbon-14 in the atmosphere has varied over time (1); so dates are converted to calendar years using tree rings and other records (1).
Question 47 · Spec T3, Key Idea 3 · Varves
State the assumption made when using varves for dating. [1 mark]
Answer:
That each pair of light and dark layers represents one year.
Question 48 · Spec T3, Key Idea 3 · Dendrochronology
Explain how cross-dating improves tree-ring chronologies. [2 marks]
Answer:
Overlapping ring patterns from different trees are matched (1); extending the record back in time and identifying missing rings (1).
Question 49 · Spec T3, Key Idea 3 · Tephrochronology
Explain why volcanic ash layers are useful time markers. [2 marks]
Answer:
Ash from one eruption is spread over a large area almost instantly (1); and has a distinctive chemistry, so it can be correlated (1).
Question 50 · Spec T3, Key Idea 3 · Dating
A pollen change lies above a dated ash and below dated peat. State what this tells you about its age. [1 mark]
Answer:
The change is younger than the ash and older than the peat.

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