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G2: Rock Deformation

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

How are faults classified, recognised and related to the stress that formed them?

The classification of faults (normal, reverse, thrust, strike-slip) by the relative movement of the hanging wall and footwall and by the stress regime, the terminology of fault planes (dip, throw, heave, slickensides), and the recognition of faults in the field and on maps.
A focused WJEC and Eduqas A-Level Geology G2 answer on the classification of normal, reverse, thrust and strike-slip faults by hanging-wall and footwall movement and stress regime, the terms used to describe fault planes (dip, throw, heave, slickensides, fault breccia), and how faults are recognised in the field and interpreted on geological maps.
13 min answer →

How are folds described, classified and interpreted?

The geometry of folds (limbs, axial plane, hinge, fold axis, interlimb angle), the classification of folds (anticline, syncline, symmetrical, asymmetrical, overturned, recumbent, isoclinal) and the use of fold style to interpret the direction and intensity of compression.
A focused WJEC and Eduqas A-Level Geology G2 answer on fold geometry (limbs, hinge, axial plane, fold axis, interlimb angle), the classification of anticlines and synclines and of symmetrical, asymmetrical, overturned, recumbent and isoclinal folds, and how fold style is read to deduce the direction and intensity of compression.
13 min answer →

How do rocks respond to stress, and what controls brittle versus ductile behaviour?

The concepts of stress and strain, the difference between compressional, tensional and shear stress, elastic, brittle and ductile behaviour, and the factors (temperature, confining pressure, strain rate, rock type and fluids) that control how a rock deforms.
A focused WJEC and Eduqas A-Level Geology G2 answer on stress and strain, the three stress regimes, elastic, brittle and ductile behaviour, and the controls (temperature, confining pressure, strain rate, rock competence and fluid pressure) that decide whether a rock fractures or flows when deformed.
13 min answer →

How are unconformities and combined structures used to reconstruct a tectonic history?

The types of unconformity (angular, disconformity, nonconformity) and their significance, the structures of mountain belts (nappes, thrust stacks), and the use of cross-cutting relationships and superposition to reconstruct the sequence of tectonic events.
A focused WJEC and Eduqas A-Level Geology G2 answer on the three types of unconformity and what each records, the structures of orogenic belts such as nappes and thrust stacks, and how cross-cutting relationships, superposition and unconformities are combined to reconstruct the sequence of folding, faulting, intrusion, uplift and erosion in a region.
13 min answer →