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F3: Time and Change

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How are fossils preserved and used to correlate and date rocks?

The conditions and modes of fossil preservation, the principle of faunal succession, and the use of zone (index) fossils to correlate and relatively date strata.
A focused answer to WJEC and Eduqas A-Level Geology F3 on fossils, covering the conditions and modes of fossil preservation, the principle of faunal succession, and how zone (index) fossils are used to correlate strata between areas and to relatively date rocks.
13 min answer →

How is the numerical age of a rock measured?

The principle of radiometric dating using radioactive decay and half-life, the parent-to-daughter ratio, the choice of isotope system, and the assumptions and limitations of the method.
A focused answer to WJEC and Eduqas A-Level Geology F3 on absolute dating, covering radioactive decay and half-life, calculating an age from the parent-to-daughter ratio, the choice of isotope system (uranium-lead, potassium-argon, carbon-14), and the assumptions and limitations of radiometric dating.
13 min answer →

How do we work out the order of geological events from the rock record?

The principles of relative dating (superposition, original horizontality, cross-cutting relationships, included fragments and unconformities) and how they are combined to establish the sequence of geological events.
A focused answer to WJEC and Eduqas A-Level Geology F3 on relative dating, covering the principles of superposition, original horizontality, cross-cutting relationships, included fragments and unconformities, and how they are combined to reconstruct the order of geological events in a sequence.
13 min answer →

How is the geological timescale built and divided?

The structure of the geological timescale (eons, eras, periods and epochs), how it is built from relative and absolute dating, and the major events that define its main boundaries.
A focused answer to WJEC and Eduqas A-Level Geology F3 on the geological timescale, covering its hierarchy of eons, eras, periods and epochs, how it is constructed from combined relative and absolute dating, and the major events (mass extinctions and the appearance of major groups) that define its principal boundaries.
12 min answer →