What does the Quaternary geology option (T3) cover?

T3 covers the most recent geological period, the Quaternary, and its repeated glacial and interglacial cycles. It includes the evidence for the cycles (glacial and periglacial deposits and landforms, ocean-sediment and ice-core oxygen isotopes, pollen and fossils), glacial and periglacial processes, the dating of Quaternary events (radiocarbon, luminescence, isotope stages, varves) and the causes of the cycles, especially the Milankovitch orbital variations amplified by feedbacks.

What does the geological evolution of Britain option (T4) cover?

T4 covers how Britain's geology formed through the Phanerozoic. It includes the main orogenies (Caledonian, from Iapetus Ocean closure; Variscan, from a southern collision; and Alpine, the distant effect of the Africa-Europe collision), the rocks and structures each produced, and Britain's steady northward drift, recorded by climate-sensitive rocks such as Carboniferous equatorial coals and Permo-Triassic subtropical desert sandstones and evaporites.

What does the geology of the lithosphere option (T5) cover?

T5 covers the structure and behaviour of the lithosphere. It includes the lithosphere and asthenosphere (a mechanical distinction), the structure and formation of oceanic and continental crust, the geophysical evidence for the Earth's interior (seismic, gravity, magnetic and heat-flow methods), and the processes of isostasy (the buoyant balance of the lithosphere on the asthenosphere, explaining mountain roots and post-glacial rebound) and crustal recycling through the Wilson cycle.

How do the optional themes connect to the rest of the course?

Each option deepens core content. T3 applies the palaeoclimate ideas of G3 to the Quaternary; T4 applies plate tectonics (F4), structures (G2) and palaeoclimate (G3) to the British record; and T5 deepens the Earth-structure and tectonics content of F4 with geophysics and isostasy. All three reward the same skill: applying established principles to interpret evidence from a particular setting.

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WJEC A-Level Geology optional Geological Themes (T3, T4, T5): a deep dive on Quaternary geology, the evolution of Britain and the lithosphere

Q: What are the optional Geological Themes in WJEC A-Level Geology?

Alongside the two compulsory themes (T1 Geohazards and T2 Geological Map Applications), the specification offers three optional Geological Themes, of which a learner studies one: T3 Quaternary geology, T4 geological evolution of Britain and T5 geology of the lithosphere. Each applies the core content to a particular field, and questions are set on the option a centre has taught.

A deep-dive WJEC and Eduqas A-Level Geology guide to the three optional Geological Themes, of which a learner studies one: T3 Quaternary geology, T4 geological evolution of Britain and T5 geology of the lithosphere. Covers glacial cycles and Milankovitch forcing, the orogenies and northward drift of Britain, and the lithosphere, crust types, geophysics and isostasy.

Generated by Claude Opus 4.815 min readWJECUpdated 2026-06-16

Reviewed by: AI editorial process; not yet individually human-reviewed

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What the optional themes demand
T3 Quaternary geology
T4 Geological evolution of Britain
T5 Geology of the lithosphere
Check your knowledge

What the optional themes demand

The three optional themes each take a body of core content and apply it in depth to a particular field. A centre teaches one, and the examination sets questions on it. The shared skill is interpretation: reading evidence (a Quaternary sequence, a British succession, geophysical data) through established principles, and explaining what it shows. Each theme has its own dot-point page; this overview connects all three.

T3 Quaternary geology

The Quaternary records repeated glacial and interglacial cycles, reconstructed from glacial and periglacial deposits and landforms, ocean-sediment and ice-core oxygen isotopes and pollen. Glaciers erode by abrasion and plucking and deposit unsorted till and sorted outwash. The cycles are paced by Milankovitch orbital variations (eccentricity, obliquity, precession) and amplified by ice-albedo and carbon dioxide feedbacks.

T4 Geological evolution of Britain

Britain was shaped by three orogenies: the Caledonian (Iapetus closure, NE-SW grain), the Variscan (southern collision, north-verging folds and south-west granites) and the Alpine (gentle folding of the south-east). Through the Phanerozoic Britain drifted north, recorded by Carboniferous equatorial coals, Permo-Triassic subtropical desert beds and younger warm-sea rocks.

T5 Geology of the lithosphere

The lithosphere is the rigid plate-forming shell; the asthenosphere is the ductile layer beneath. Oceanic crust is thin, dense, basaltic and young; continental crust is thick, less dense, granitic and old. The interior is read from seismic, gravity, magnetic and heat-flow data, and isostasy is the buoyant balance that explains mountain roots and post-glacial rebound.

Check your knowledge

Attempt these under timed conditions, then check against the solutions.

Distinguish till from outwash. (2 marks)
Name the three Milankovitch cycles. (3 marks)
Name the ocean whose closure caused the Caledonian orogeny. (1 mark)
State the climate Britain experienced in the Carboniferous and its evidence. (2 marks)
Distinguish the lithosphere from the asthenosphere. (2 marks)
Explain why parts of Scotland are still rising today. (2 marks)

Sources & how we know this

WJEC Eduqas A-level Geology specification — WJEC Eduqas (2017)