PAU Geología y Ciencias Ambientales (Cantabria) common mistakes
PAU Geología y Ciencias Ambientales (Cantabria) · Understand the traps and how to avoid them.
When asked to order geological events from a cross-section or stratigraphic column, the candidate lists the rock types present instead of establishing a relative-age sequence (which unit is older, which structure cuts which), and treats a folded or faulted contact as a simple superposition.
Candidates memorise the principle of superposition as a slogan but never practise applying cross-cutting, inclusion and faunal succession relations to a drawn section, so under exam pressure they describe what they see rather than reconstruct the history.
What to do instead
For every section, write a numbered event list before writing prose: deposition of each bed, folding, intrusion, faulting, erosion/unconformity, then the most recent surface processes. State the principle that justifies each step (cross-cutting relationships, inclusions, superposition, faunal succession) and check that the order is internally consistent.
The candidate confuses the direction of plate movement with the type of boundary, labelling a convergent margin as divergent because the map shows two plates 'separating' along a ridge drawn on the diagram, or assigning subduction to a transform fault.
Schematic maps use arrows and symbols that look similar at a glance, and candidates learn boundary names without linking them to the specific landforms (trench, ridge, fracture zone) and seismic/volcanic signatures that identify each.
What to do instead
Build a three-column table: boundary type, diagnostic landforms, diagnostic seismicity and volcanism. Practise identifying boundaries from landform evidence alone (oceanic trench plus volcanic arc means convergence; mid-ocean ridge with shallow seismicity means divergence; offset magnetic stripes and transform faults mean conservative margins) and always justify the label from the evidence given.
When describing metamorphism, the candidate names a rock (for example 'marble' or 'schist') without stating the protolith, the grade or the agent of metamorphism, and treats metamorphic grade as simply 'more heat' rather than a pressure-temperature path.
Rock names are learned as vocabulary lists in the minerals and rocks topic, and the link between protolith, grade and tectonic setting is never rehearsed, so the candidate answers with a label instead of a process.
What to do instead
Answer metamorphism questions with a three-part sentence: protolith plus agent (heat, pressure, fluids) plus resulting rock and grade. Learn paired examples (limestone to marble, shale to slate to schist to gneiss, basalt to greenschist to amphibolite) and connect high-pressure low-temperature assemblages to subduction and high-temperature low-pressure assemblages to contact aureoles or rifting.
The candidate treats weathering and erosion as synonyms and describes a landscape as 'eroded by weathering', failing to separate the in-situ breakdown of rock from the transport of the debris, and omitting the transport agent and depositional environment in sedimentary questions.
The external geodynamics topic is taught as a single cycle and candidates compress the stages into one verb, losing the marks awarded for distinguishing processes and for naming the agent and environment of deposition.
What to do instead
Use a fixed four-step template for every external-process question: weathering (physical, chemical, biological, with the specific reaction or mechanism), erosion (the agent removing material), transport (agent and distance, with evidence such as rounding or sorting), and sedimentation (environment and resulting rock). Name the environment explicitly (fluvial, aeolian, glacial, marine, lacustrine) and give the diagnostic feature that supports it.
In mineral identification, the candidate relies on colour alone to name a mineral and ignores cleavage, hardness, lustre, streak and crystal form, so dark micas, amphiboles and pyroxenes are confused and quartz is called calcite or vice versa.
Colour is the most visually obvious property but the least diagnostic, and candidates have not practised the systematic key that uses hardness and cleavage first, so they jump to a name from a single observation.
What to do instead
Identify in a fixed order: lustre (metallic or non-metallic), hardness against a fingernail, copper coin, glass and steel, cleavage or fracture and its angle, streak, then colour. Memorise the discriminating pairs (calcite fizzes in dilute acid and has rhombohedral cleavage; quartz has conchoidal fracture and hardness 7; halite commonly has cubic cleavage; gypsum is hardness 2). Justify each identification with at least two properties.
The candidate answers a climate question by listing greenhouse gases or 'global warming' as a cause, without distinguishing natural forcing (orbital, solar, volcanic, albedo, ocean circulation) from anthropogenic forcing, and without separating weather from climate or the atmosphere's role from the ocean's.
Climate is taught through headline narratives rather than as a system of energy balance and feedbacks, so candidates reproduce slogans and cannot apply the concepts to a data-interpretation question.
What to do instead
Frame every climate answer as an energy-balance argument: incoming solar radiation, albedo, absorption, re-emission, greenhouse effect and feedbacks (ice-albedo, water vapour, cloud). Separate timescales explicitly (weather hours to days, climate decades or more) and name the specific forcing and its evidence (ice cores, isotope ratios, instrumental records) rather than asserting causation.
When interpreting a geological map, the candidate reads the contour or topographic lines as geological boundaries, or gives a dip direction from the V-rule without checking which way the ground slopes, producing a dip that contradicts the outcrop pattern.
Map interpretation is a spatial skill that requires combining topography, strike lines and outcrop geometry, and candidates who have not practised the V-in-a-valley rule or the outcrop-width rule guess from the shape of the lines alone.
What to do instead
Identify topography and geological contacts separately. Compare bed dip, strike and valley gradient, and test the interpretation against a correctly scaled cross-section. An outcrop V is not an unconditional rule that its point equals dip direction.
The candidate treats a natural hazard as a single event and omits vulnerability and exposure, so a risk question is answered with 'the earthquake was strong' rather than a risk equation, and mitigation measures are listed without linking them to the specific hazard.
Hazard, vulnerability and risk are conflated in everyday language, and candidates have not practised separating the physical process from the human and economic factors that turn it into a disaster.
What to do instead
Answer with the explicit relationship: risk is a function of hazard, exposure and vulnerability. For each hazard name the triggering process, the primary and secondary effects, the exposed elements, and then match mitigation to mechanism (building codes and base isolation for seismic risk, land-use zoning and drainage for floods, slope stabilisation and reforestation for mass movements).