Eduqas A-level Geology · T4

Geological evolution of Britain (option)

50 exam-style questions with answers for T4 Geological evolution of Britain (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.

All 50 questions and answers

Question 1 · Spec T4, Key Idea 1 · British geology
Explain why Britain is useful for studying a long geological history. [2 marks]
Answer:
Rocks of almost every geological period are exposed in a small area (1); recording many different environments and tectonic settings (1).
Question 2 · Spec T4, Key Idea 3 · Terranes
Define the term 'lithotectonic terrane'. [2 marks]
Answer:
A fault-bounded region with its own distinctive geological history (1); joined to other terranes by tectonic processes (1).
Question 3 · Spec T4, Key Idea 3 · Terranes
Explain why northern and southern Britain had separate early histories. [2 marks]
Answer:
They were on different continents (Laurentia and Avalonia) (1); separated by the Iapetus Ocean until the Caledonian orogeny (1).
Question 4 · Spec T4, Key Idea 3 · Caledonian orogeny
State when the Caledonian orogeny occurred. [1 mark]
Answer:
In several phases from the Ordovician to the Early Devonian.
Question 5 · Spec T4, Key Idea 3 · Caledonian orogeny
State the trend of Caledonian structures in Britain. [1 mark]
Answer:
North-east to south-west.
Question 6 · Spec T4, Key Idea 3 · Caledonian orogeny
Explain how the closure of the Iapetus Ocean caused the Caledonian orogeny. [2 marks]
Answer:
Oceanic crust was subducted until the continents on either side collided (1); causing folding, metamorphism, crustal thickening and granite intrusion (1).
Question 7 · Spec T4, Key Idea 3 · Variscan orogeny
State when the main Variscan deformation of southern Britain occurred. [1 mark]
Answer:
Late Carboniferous to early Permian.
Question 8 · Spec T4, Key Idea 3 · Variscan orogeny
State the trend of Variscan structures in southern Britain. [1 mark]
Answer:
East-west.
Question 9 · Spec T4, Key Idea 3 · Variscan orogeny
Explain why Variscan deformation becomes weaker northwards. [2 marks]
Answer:
Britain lay north of the main collision zone, in the foreland (1); so stress and strain decreased away from it, although older faults could still be reactivated (1).
Question 10 · Spec T4, Key Idea 3 · Alpine orogeny
Explain how the Alpine orogeny affected Britain. [2 marks]
Answer:
Compression transmitted from the collision far to the south (1); reactivated older faults and formed gentle folds such as the Weald anticline (1).
Question 11 · Spec T4, Key Idea 3 · Orogenies
Explain how metamorphic and igneous rocks help reconstruct an ancient mountain belt. [2 marks]
Answer:
Metamorphic minerals show the pressures and temperatures of burial (1); and intrusions with radiometric ages date the magmatism (1).
Question 12 · Spec T4, Key Idea 3 · Orogenic granites
Explain why crustal thickening during an orogeny can form granite. [2 marks]
Answer:
Thickened crust is buried deeper and becomes hotter (1); so the lower crust partially melts to form granite magma (1).
Question 13 · Spec T4, Key Idea 3 · Orogenies
Explain why some areas have orogenic granites while others only show folding. [2 marks]
Answer:
The areas were at different depths and positions in the orogen (1); so not all reached temperatures high enough to melt (1).
Question 14 · Spec T4, Key Idea 3 · Palaeogene igneous province
State the tectonic event linked to the Palaeogene igneous province of north-west Britain. [1 mark]
Answer:
The opening of the North Atlantic Ocean.
Question 15 · Spec T4, Key Idea 3 · Palaeogene igneous province
State three types of igneous feature in the Palaeogene igneous province. [3 marks]
Answer:
Any three from: flood basalt lava sequences (1); dyke swarms (1); sills (1); central igneous complexes, e.g. Skye and Mull (1).
Question 16 · Spec T4, Key Idea 3 · Palaeogene igneous province
State the age range of the Palaeogene igneous province. [1 mark]
Answer:
About 60.5–54.5 Ma.
Question 17 · Spec T4, Key Idea 3 · Geophysics
Explain why geophysical surveys are used as well as outcrops to study British geology. [2 marks]
Answer:
Many structures are buried beneath younger rocks or lie offshore (1); geophysics shows their shape and extent below the surface (1).
Question 18 · Spec T4, Key Idea 3 · Gravity surveys
Explain how Bouguer gravity anomalies help investigate buried structures. [2 marks]
Answer:
They show differences in rock density below the surface (1); negative anomalies may show sedimentary basins or granites, positive anomalies dense basement (1).
Question 19 · Spec T4, Key Idea 3 · Magnetic surveys
Explain how magnetic surveys help where old rocks are buried. [1 mark]
Answer:
They detect magnetic rocks such as basalt intrusions and basement beneath the cover.
Question 20 · Spec T4, Key Idea 3 · Boreholes
Explain why deep boreholes such as Mochras are important. [2 marks]
Answer:
They provide actual rock samples from below the surface (1); testing correlations and interpretations made from outcrops and geophysics (1).
Question 21 · Spec T4, Key Idea 3 · Seismic reflection
Explain how offshore seismic reflection links onshore and offshore geology. [1 mark]
Answer:
Reflecting layers and faults can be traced beneath the sea to connect with rocks exposed on land.
Question 22 · Spec T4, Key Idea 3 · Reactivation
Explain why younger basins often follow older structural trends. [2 marks]
Answer:
Old faults are lines of weakness (1); which are reactivated by later stress, controlling where basins form (1).
Question 23 · Spec T4, Key Idea 2 · Palaeomagnetism
State what remanent magnetism in a rock can tell us about Britain's former position. [1 mark]
Answer:
Its palaeolatitude (but not its longitude).
Question 24 · Spec T4, Key Idea 2 · Palaeomagnetism
Explain why bedding must be restored to horizontal before using a palaeomagnetic direction. [2 marks]
Answer:
Later tilting rotated the magnetisation (1); so restoring the bedding gives the original direction (1).
Question 25 · Spec T4, Key Idea 2 · Palaeomagnetism
Explain why a palaeomagnetic study must test for remagnetisation. [2 marks]
Answer:
Later heating or chemical change can reset the magnetisation (1); so the direction would record the later event, not the original age (1).
Question 26 · Spec T4, Key Idea 2 · Palaeomagnetism
Use tan(I) = 2 tan(latitude) to calculate palaeolatitude when inclination I = 45°. [2 marks]
Answer:
tan(latitude) = tan 45° ÷ 2 = 0.5 (1); latitude = 26.6° (1).
Question 27 · Spec T4, Key Idea 2 · Palaeomagnetism
State the palaeolatitude shown by a near-horizontal magnetic inclination. [1 mark]
Answer:
Near the equator.
Question 28 · Spec T4, Key Idea 2 · Apparent polar wander
Explain how apparent polar wander paths show whether two regions moved together. [2 marks]
Answer:
If the paths match, the regions were on the same plate (1); if they differ, the regions moved separately and were later joined (1).
Question 29 · Spec T4, Key Idea 2 · Climate indicators
Explain why red beds or evaporites alone cannot prove a precise latitude. [2 marks]
Answer:
Hot, dry climates occur over a range of latitudes in both hemispheres (1); so palaeomagnetism is needed to give a more precise latitude (1).
Question 30 · Spec T4, Key Idea 2 · Northward drift
Explain how changing rock types support Britain's northward drift. [2 marks]
Answer:
Britain moved from southern latitudes through desert, then equatorial, then desert zones (1); recorded by glacial, tropical reef, coal and red bed deposits in turn (1).
Question 31 · Spec T4, Key Idea 1 · Neoproterozoic
State the major tectonic event of the Neoproterozoic. [1 mark]
Answer:
The break-up of the supercontinent Rodinia.
Question 32 · Spec T4, Key Idea 1 · Neoproterozoic
Explain why the Port Askaig tillite is important. [2 marks]
Answer:
It is evidence of Neoproterozoic glaciation in Britain (1); used to support the Snowball Earth hypothesis (1).
Question 33 · Spec T4, Key Idea 1 · Neoproterozoic
State the significance of Charnia. [1 mark]
Answer:
It is an Ediacaran fossil, one of the earliest complex multicellular organisms, from Charnwood Forest.
Question 34 · Spec T4, Key Idea 1 · Early Palaeozoic
Name the ocean that separated northern and southern Britain in the Early Palaeozoic. [1 mark]
Answer:
The Iapetus Ocean.
Question 35 · Spec T4, Key Idea 1 · Early Palaeozoic
State the evidence for shallow seas in the Cambrian and Silurian of Britain. [2 marks]
Answer:
Shallow-water sandstones and limestones with ripples and cross-bedding (1); fossils such as corals, brachiopods and trilobites (1).
Question 36 · Spec T4, Key Idea 1 · Early Palaeozoic
Explain how graptolitic shales and turbidites show Ordovician deep water. [2 marks]
Answer:
Black graptolitic shales formed in deep, quiet, anoxic water (1); turbidites were deposited by turbidity currents on the deep sea floor (1).
Question 37 · Spec T4, Key Idea 1 · Mid Palaeozoic
Name the continent formed by the Caledonian orogeny. [1 mark]
Answer:
Euramerica (Laurussia, the Old Red Sandstone continent).
Question 38 · Spec T4, Key Idea 1 · Devonian
Explain how Devonian conglomerates and sandstones record erosion of mountains. [2 marks]
Answer:
The Caledonian mountains were rapidly eroded (1); and the debris was deposited by rivers and alluvial fans as Old Red Sandstone (1).
Question 39 · Spec T4, Key Idea 1 · Devonian
Explain why a red colour does not prove that a sandstone formed in desert dunes. [2 marks]
Answer:
Iron oxide coatings form in many hot, oxidising land environments, including rivers (1); dune evidence needs well-rounded grains and large-scale cross-bedding (1).
Question 40 · Spec T4, Key Idea 1 · Carboniferous
State the evidence for equatorial swamp forests in the Coal Measures. [2 marks]
Answer:
Coal seams and plant fossils (1); seat earths with roots below the coal (1).
Question 41 · Spec T4, Key Idea 1 · Carboniferous
Explain why coal seams alternate with other sediments in Carboniferous cyclothems. [2 marks]
Answer:
Changes in relative sea level and sediment supply (1); repeatedly drowned the swamps and built up deltas again (1).
Question 42 · Spec T4, Key Idea 1 · Late Palaeozoic
Explain how the Variscan orogeny is linked to the formation of Pangaea. [1 mark]
Answer:
It was caused by the collision of Gondwana with Laurussia, assembling Pangaea.
Question 43 · Spec T4, Key Idea 1 · Permo-Triassic
State three pieces of evidence for an arid Permo-Triassic environment. [3 marks]
Answer:
Any three from: red beds (1); desert dune sandstones with large cross-bedding (1); desiccation cracks (1); evaporites (1).
Question 44 · Spec T4, Key Idea 1 · Permo-Triassic
Explain why evaporites indicate restricted water bodies. [2 marks]
Answer:
The water had limited connection to the open ocean (1); so evaporation concentrated the salts until they precipitated (1).
Question 45 · Spec T4, Key Idea 1 · Jurassic
State evidence for a shallow marine shelf in the Jurassic. [2 marks]
Answer:
Marine fossils such as ammonites, bivalves and corals (1); oolitic limestones and shallow-water sedimentary structures (1).
Question 46 · Spec T4, Key Idea 1 · Mesozoic
Explain why thick sediments accumulated in the North Sea in the Mesozoic. [2 marks]
Answer:
Rifting created fault-bounded basins (1); and continued subsidence allowed thick sequences to build up (1).
Question 47 · Spec T4, Key Idea 1 · Cretaceous
State the conditions recorded by Cretaceous chalk. [2 marks]
Answer:
High global sea level that flooded most of Britain (1); warm, clear water with little land-derived sediment (1).
Question 48 · Spec T4, Key Idea 1 · Palaeogene
Explain how alternating marine and non-marine Palaeogene deposits form. [2 marks]
Answer:
Changes in relative sea level moved the shoreline back and forth (1); producing transgressive and regressive sequences (1).
Question 49 · Spec T4, Key Idea 1 · Cenozoic
Explain how parts of Britain were uplifted while the North Sea continued to subside. [1 mark]
Answer:
Different areas responded differently to tectonic forces, so Britain did not move as one rigid block.
Question 50 · Spec T4, Key Idea 1 · Palaeogeography
State three types of evidence used to reconstruct the palaeogeography of Britain. [3 marks]
Answer:
Any three from: fossils (1); sedimentary environments (1); palaeomagnetism (1); radiometric ages (1); structures and igneous activity (1); subsurface data (1).

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