GEOG20009 Lecture 15: Lecture 15 Detailed Notes Landscapes & Diversity GEOG 20009
15 May 2018
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LECTURE 15: LANDFORMS AND SOILS
• Tectonics: formation of topography – endogenic (Earth interior driven) processes
o Volcanism
o Uplift at convergent plate boundaries
• Exogenic (external – climate) and endogenic (internal – tectonic) processes create topography and landforms –
shape Earth’s surface
• The rock cycle: weathering and erosion, transport and deposition
o Weathering: breaking down of rocks, soil and minerals (produces sediment)
o Erosion: action of surface processes to remove sediment, soil and rock
o Transport & Deposition: sediment transport and deposition by varying
agents (water, wind, gravity, ice) – creates a wind range of landforms
• Geomorphology: the scientific study of the origin (form and process) and evolution (dynamics) of topographic
features
o Influences on life: landform changes and allopatric speciation (vicariance) – river course change has
different mechanisms of influencing evolution
▪ Short time scale: e.g dust – biogeochemical cycles – cyanobacterial blooms in Europe
associated with Saharan precipitation cycles
EARTH SURFACE PROCESSES AND LIFE
• Processes lead to changes in communities – habitat fragmentation
• Disturbance and succession – recolonization
• As disturbance level and sediment supply decrease, specific adaptations of
organisms to geomorphologic disturbances decrease
o Physical processes dominate landform when disturbance level is high
o Organisms dominate landform when disturbance level is low
Landform Feedbacks
• Fluvial Levee: Flooding – sedimentation – topography – vegetation –
sedimentation
• Vegetation stabilise river banks, and reduce sedimentation, and affect channel
form
• Parabolic Dunes: organism stabilize sediment to reach an equilibrium – counter-
act physical wind processes
• All based around equilibriums
Community – landform – organism
• Organisms modify geomorphology by transforming non-living materials and modulating their fluxes via mechanical
or other means
• Biogeomorphology: different types of landform modification, species involved called geomorphic-engineer species
o Bioerosion: organisms as agents of weathering and erosion (roots, fungi, lichen, bacteria)
o Bioconstruction/bioaccumulation: coral reefs, termite mounds
o Biostabilisation
o Bioturbation: faunal impact – geomorphic impacts of animals (sediment dynamics) – e.g. imprints of
elephants
▪ Earthworms: create residual (surface mounds and mixed soil) and functional (galleries –
mobility tunnels into the soil) landform components
• Ecosystem Engineers: biota that can modify their physical habitat so its beneficial to them
o Cause for environmental niche construction – increases ecosystem functioning (think keystone species)
o Different from geomorphic-engineer species
Agents: Water - mechanical, ice,
gravity, wind, water (dissolution
– chemical)
Beavers
• Keystone species: species that play a critical role in maintaining the structure of an ecological community
• Dams and water bodies, they create: habitats for species, filter waters, filter sediment
• Ecosystem engineers! – ponds created by dams allow them to build homes
• Responsible for farm land – provide water – soil quality linked to ecosystems productivity
Document Summary
Tectonics: formation of topography endogenic (earth interior driven) processes: volcanism, uplift at convergent plate boundaries. Exogenic (external climate) and endogenic (internal tectonic) processes create topography and landforms shape earth"s surface. Agents: water - mechanical, ice, gravity, wind, water (dissolution. Chemical) agents (water, wind, gravity, ice) creates a wind range of landforms: geomorphology: the scientific study of the origin (form and process) and evolution (dynamics) of topographic features. Influences on life: landform changes and allopatric speciation (vicariance) river course change has different mechanisms of influencing evolution. Short time scale: e. g dust biogeochemical cycles cyanobacterial blooms in europe associated with saharan precipitation cycles. Earth surface processes and life: disturbance and succession recolonization, as disturbance level and sediment supply decrease, specific adaptations of. Processes lead to changes in communities habitat fragmentation organisms to geomorphologic disturbances decrease: physical processes dominate landform when disturbance level is high, organisms dominate landform when disturbance level is low.
