← Geology syllabus

EnglandGeology

Module 3: Global tectonics - Plate tectonics

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How are earthquakes generated and measured, and how do we locate an epicentre?

Earthquakes: focus and epicentre; the elastic rebound mechanism; the types of seismic wave (P, S and surface waves) and their properties; magnitude (the logarithmic Richter and moment magnitude scales) versus intensity (Modified Mercalli); the use of P and S wave arrival times and travel-time graphs to locate an epicentre by triangulation.
A focused answer to the OCR H414 dot point on earthquakes. Covers focus and epicentre, elastic rebound, P, S and surface waves, the difference between magnitude (Richter and moment magnitude) and intensity (Modified Mercalli), and how P and S wave travel times and triangulation locate an epicentre.
13 min answer →

How do rocks deform under stress, and how do we read folds, faults and unconformities?

Geological structures: the response of rocks to stress (folds and faults); fold elements and types (anticline and syncline, limb, hinge and axial plane); fault types and the stress regime they record (normal from tension, reverse and thrust from compression, strike-slip from shear); joints; dip and strike; the recognition and significance of unconformities (angular unconformity, disconformity and nonconformity).
A focused answer to the OCR H414 dot point on geological structures. Covers folds (anticline, syncline, limb, hinge, axial plane), fault types and the stress they record (normal, reverse, thrust, strike-slip), joints, dip and strike, and the recognition and significance of angular unconformities, disconformities and nonconformities.
13 min answer →

What happens at the three types of plate margin, and what features do they produce?

Plate margins: the processes and features of constructive (divergent), destructive (convergent) and conservative (transform) margins; the sub-types of destructive margin (ocean-continent, ocean-ocean and continent-continent collision); the Benioff zone and subduction; the characteristic rocks, structures, earthquakes and volcanoes produced at each margin type.
A focused answer to the OCR H414 dot point on plate margins. Covers constructive (divergent), destructive (convergent) and conservative (transform) margins, the ocean-continent, ocean-ocean and continent-continent sub-types, the Benioff zone and subduction, and the characteristic rocks, structures, earthquakes and volcanoes of each.
13 min answer →

What evidence built the theory of plate tectonics, and what drives the plates?

Plate tectonics: the development of the theory from continental drift (Wegener's evidence) through sea-floor spreading to plate tectonics; the evidence of palaeomagnetism and symmetrical magnetic striping at mid-ocean ridges; the increasing age of oceanic crust away from ridges; the driving mechanisms of mantle convection, ridge push and slab pull.
A focused answer to the OCR H414 dot point on the development of plate tectonics. Covers Wegener's continental drift evidence, sea-floor spreading, palaeomagnetism and symmetrical magnetic striping, the increasing age of oceanic crust away from ridges, and the driving mechanisms of mantle convection, ridge push and slab pull.
13 min answer →

What controls how a volcano erupts, and what products and landforms result?

Volcanism: the control of magma composition (silica content), viscosity and dissolved gas on eruption style; the contrast between basaltic effusive eruptions and andesitic or rhyolitic explosive eruptions; volcanic products (lava, tephra, pyroclastic flows and gases); volcanic landforms (shield volcanoes, stratovolcanoes, calderas and fissures); the link between volcanism and plate setting.
A focused answer to the OCR H414 dot point on volcanism. Covers how silica content, viscosity and gas control eruption style, the contrast between basaltic effusive and andesitic or rhyolitic explosive eruptions, volcanic products (lava, tephra, pyroclastic flows, gases), the landforms (shield, stratovolcano, caldera, fissure), and the link to plate setting.
12 min answer →