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Time, past life and past climates

6 dot points across 6 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

What does the fossil record show about evolution and the major changes in life through time?

Evolution and the fossil record: the evidence for evolution preserved in successive strata; modes of evolutionary change (gradualism and punctuated equilibrium); the use of evolutionary trends in lineages for dating; the major mass extinctions and their possible causes; and the broad pattern of the history of life through the geological time scale.
A focused answer to the Eduqas Geology statement on evolution. Covers the fossil evidence for evolution, gradualism versus punctuated equilibrium, evolutionary trends used in dating, the major mass extinctions and their causes, and the broad history of life through geological time.
13 min answer →

How do organisms become fossils, and which fossils are most useful for dating and correlation?

Fossils, preservation and index fossils: the modes of fossil preservation (unaltered hard parts, recrystallisation, replacement, moulds and casts, carbonisation, trace fossils); the conditions that favour preservation; and the characteristics that make a good index (zone) fossil for biostratigraphic correlation.
A focused answer to the Eduqas Geology statement on fossils. Covers the modes of fossil preservation, the conditions that favour fossilisation, the difference between body and trace fossils, and the characteristics of a good index (zone) fossil for biostratigraphic correlation.
13 min answer →

How do rocks and fossils let us reconstruct past environments and climates?

Palaeoenvironments and palaeoclimate proxies: the use of fossils, sedimentary structures and lithology to reconstruct past environments; palaeoclimate proxies (for example coal, evaporites, tillites, reef limestones, oxygen isotopes and fossil leaf shape); the use of facies and Walther's law; and the evidence for past climate change recorded in the rocks.
A focused answer to the Eduqas Geology statement on palaeoenvironments. Covers reconstructing past environments from fossils, sedimentary structures and lithology, palaeoclimate proxies such as coal, evaporites and tillites, facies and Walther's law, and the rock evidence for past climate change.
13 min answer →

What does the Quaternary record tell us about ice ages, and how do we reconstruct them?

Quaternary glacial and periglacial geology (Component 3 option): glacial and periglacial processes and their deposits and landforms (till, moraines, drumlins, eskers, outwash, periglacial features); the evidence for Quaternary climate change (glacial-interglacial cycles, oxygen isotopes, ice cores); sea-level change; and the methods used to date and reconstruct Quaternary environments.
A focused answer to the Eduqas Geology Component 3 Quaternary option. Covers glacial and periglacial processes and deposits (till, moraines, drumlins, eskers, outwash), the evidence for Quaternary climate change from oxygen isotopes and ice cores, sea-level change, and the dating and reconstruction of Quaternary environments.
14 min answer →

How do radioactive isotopes give the age of a rock in years?

Radiometric dating and half-life: radioactive decay and the concept of half-life; the use of parent-to-daughter ratios to calculate absolute ages; the main dating methods and their suitable age ranges (for example uranium-lead, potassium-argon, rubidium-strontium and carbon-14); the assumptions and limitations of radiometric dating; and the construction of the absolute geological time scale.
A focused answer to the Eduqas Geology statement on radiometric dating. Covers radioactive decay and half-life, calculating absolute ages from parent-to-daughter ratios, the main dating methods and their ranges, the assumptions and limitations, and how the absolute time scale is built.
14 min answer →

How do we work out the order of geological events without knowing their ages in years?

Relative dating and stratigraphic principles: the principles of superposition, original horizontality, lateral continuity, cross-cutting relationships and included fragments; way-up (younging) indicators; and the use of these principles to reconstruct the sequence of geological events from a section or map.
A focused answer to the Eduqas Geology statement on relative dating. Covers the principles of superposition, original horizontality, lateral continuity, cross-cutting relationships and included fragments, way-up indicators, and how to reconstruct a sequence of geological events from a section or map.
13 min answer →