Physical Geography: Geomorphology, Climatology and Oceanography
Physical Geography in the KSEAB II PUC course covers geomorphology, climatology and oceanography, and the paper tests it through definition, cause-and-effect and simple numerical items. You must be able to explain why a landform or weather pattern occurs, not merely name it.
Geomorphology: two opposing force systems
- Endogenic forces (diastrophism - folding and faulting; volcanism) build relief; exogenic forces (weathering, mass wasting, erosion and deposition by rivers, wind, glaciers, groundwater and waves) wear it down.
- The plate margin decides the landform: divergent gives a mid-oceanic ridge, convergent gives a trench with an island arc or fold mountains, transform gives a fault line such as the San Andreas.
- The rock cycle links igneous, sedimentary and metamorphic rocks; only sedimentary rocks are layered and fossil-bearing.
Climatology: heat, pressure and winds
- Insolation decreases from the equator poleward; temperature falls at 6.5 °C per 1,000 m of ascent (normal lapse rate).
- Pressure belts alternate: equatorial low, subtropical high (horse latitudes), subpolar low, polar high.
- Planetary winds are deflected by the Coriolis force - to the right in the Northern Hemisphere, to the left in the Southern, and nil at the equator.
Oceanography: salinity and currents
- Mean salinity is 35 ppt; the highest values occur in subtropical seas of strong evaporation (Red Sea about 40 ppt), not at the equator, where heavy rain dilutes the water.
- Warm currents move poleward along the western margins of oceans (Gulf Stream, Kuroshio); cold currents move equatorward (Labrador, Canary, Benguela, Peru), and the resulting upwelling makes the Peru coast a rich anchovy fishery.
Worked example
A hill station at 2,200 m has sea-level temperature of 30 °C. Find its temperature. Reasoning: 2,200 m = 2.2 km; 2.2 × 6.5 = 14.3 °C of cooling; 30 − 14.3 = 15.7 °C. Always convert metres to kilometres before applying the lapse rate.
Traps that cost marks
- Calling volcanism an exogenic process.
- Placing maximum salinity at the equator instead of the subtropics.
- Forgetting that the Coriolis force is zero at the equator and strongest at the poles.
- Confusing weathering (in situ breakdown) with erosion (transport away).