3.3 Rocks and geomorphology notes

1. 3.3.1Minerals and rocks: common minerals and the rock cycle

   A mineral is a natural substance with a definite chemical composition and an orderly atomic structure; rocks are aggregates of minerals, and the rock cycle shows how igneous, sedimentary and metamorphic rocks keep changing into one another.

   Standard · 8 min · Full course
2. 3.3.2Igneous, sedimentary and metamorphic rocks compared

   Igneous rocks form from cooling magma, sedimentary rocks from compacted sediments laid in layers, and metamorphic rocks from older rocks changed by heat and pressure without melting.

   Standard · 8 min · Full course
3. 3.3.3Geomorphic processes: endogenic and exogenic forces, weathering and mass wasting

   Endogenic forces from inside the earth build relief, exogenic forces powered by the sun and gravity wear it down, and weathering and mass wasting are the first steps of that wearing down.

   Standard · 10 min · Full course
4. 3.3.4Fluvial landforms: V-shaped valleys to meanders, ox-bow lakes and deltas

   Running water is the most widespread agent of erosion: in its upper course it cuts V-shaped valleys, gorges and waterfalls, and in its lower course it builds floodplains, levees, meanders, ox-bow lakes and deltas.

   Standard · 9 min · Full course
5. 3.3.5Glacial landforms: cirques, aretes, U-shaped valleys, moraines and drumlins

   Moving ice erodes mountains into cirques, horns, aretes and U-shaped valleys, and drops unsorted debris as moraines, drumlins and eskers, with meltwater spreading sorted outwash beyond the ice.

   Standard · 7 min · Full course
6. 3.3.6Aeolian landforms: deflation hollows, mushroom rocks, dunes and loess

   In hot deserts, wind and occasional sheet floods shape the land: wind lifts and blasts sand to make deflation hollows and mushroom rocks, and drops it as dunes and loess.

   Standard · 7 min · Full course
7. 3.3.7Coastal landforms: cliffs, sea caves, spits, bars and lagoons; emergent and submergent coasts

   Waves and currents carve high rocky coasts into cliffs, caves, arches and stacks, and build low sedimentary coasts into beaches, bars, spits and lagoons; changes in sea level make coasts emergent or submergent.

   Standard · 8 min · Full course
8. 3.3.8Karst landforms: sinkholes, caves, stalactites and stalagmites

   Karst landforms form when groundwater dissolves limestone and dolomite, creating sinkholes, uvalas, lapies and caves, and then redepositing calcium carbonate as stalactites, stalagmites and pillars.

   Standard · 7 min · Full course
9. 3.3.9Mountains, plateaus and plains: types with world examples

   Mountains, plateaus and plains are the second-order landforms of the earth: mountains are classed as fold, block, volcanic and residual; plateaus by their position; and plains by whether they were built, uplifted or worn down.

   Standard · 8 min · Full course
10. 3.3.10Cycle of erosion: Davis and Penck models

    Davis saw landscapes passing through youth, maturity and old age after a quick uplift until they become a peneplain; Penck argued that uplift and erosion work together, so slope forms reflect the rate of uplift rather than the age of the landscape.

    Standard · 8 min · Full course

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