GEL341 Exam 01 Review Flashcards
Uniformitarianism/law or principle of uniformity
Stratigraphic law that states:
”Present is the key to the past.”
Assumption that earth processes have probably worked pretty much the same way they do now throughout geologic time.
Law of original horizontality
Stratigraphic law that states:
Sedimentary layers are initially deposited in horizontal layers
Law of superposition
Stratigraphic law that states:
Oldest layer is on the bottom, younger ones are on top
Law of cross-cutting [relationships/relations]
Stratigraphic law that states:
Material that is cut is older than what did the cutting
Law of lateral continuity
Stratigraphic law that states:
Sedimentary rocks are laterally continuous over large areas
Law of inclusions
Stratigraphic law that states:
Rock fragments within another rock must be older than the rock containing the fragments
Principle of faunal succession
Stratigraphic law that states:
Fossils and groups of fossiles exist for limited amounts of time, thus they appear in the rock record in a definitive pattern
Geomorphology
Investigates landforms and the processes that fashion them
Form, process, and the interrelationaships between them are central to understanding the origin and development of landforms
Form (or morphology)
Has three facets (form variables):
- Constitution
- Configuration
- Mass flow
Constitution
Chemical and physical properties described by material property variables
Configuration
Size and form described by geometry variables
Mass flow
Rates of flow described by such mass-flow variables as discharge, precipitation rate, and evaporation rate.
Form variables
Constitution, configuration, and mass flow.
Form variables contract with dynamic variables.
Dynamic variables
Chemical and mechanical properties representating the expenditure of energy and the doing of work.
e.g. power, energy flux, force, stress, momentum
Endogenic processes
Tectonic and volcanic processes driven by geological forces.
Forces orginating from inside the Earth.
Exogenic processes
Geomorphic processes driven by climatic forces.
Forces originating at or near the Earth’s surface and in the atmosphere.
Extraterrestrial processes
Forces coming from outside the Earth.
e.g. asteroid impacts
Four approaches used by geomorphologists
- Process-response (process-form or functional) approach
- Landform evolution approach
- Geographical spatial science approach
- Environmentally sensitive approach
Surface process geomorphology (or process geomorphology)
Process-response (process-form) or funcational approach to geomorphology.
Historical geomorphology
Landform evolution approach to geomorphology, which has roots in historical geology.
Broken into two groups:
(1) Quaternary geomorphology
Phanerozoic > Cenozoic > Quaternary
Quaternary = Holocene & Pleistocene
(2) Long-term geomorphology
Geographical cycle (4)
Expounded by William Morris Davis.
- Uplift takes place quickly.
- Geomorphic processes gradually wear down raw topography. (With no further complications from tectonics.)
- Slopes within landscapes decline through time – maximum slope angles slowly lessen.
- Topography reduced to an extensive, flat region close to baselevel.
*Stages = youth, maturity, old age. (Borrowed from biology.)
Peneplain
An extensive flat region close to baselevel.
Monadnocks
Occasional hills (within a peneplain) that are local erosional remnants, standing conspicuously above the general level.
Denudation chronology
Denudation = to strip bare;
a general name for processes of weathering, transport, and erosion.
Relative v. absolute chronologies
Relative = events placed in order of occurence but without accurately fixed dates
Absolute = derived from sequences dated using historical records, radiocarbon analysis, dendrochronology, luminescence, palaeomagnetism, etc.
Long-term geomorphology
Studies of landforms and landscapes older than the Quaternary, or even late Quaternary.
Includes Cenozoic, Mesozoic, and even Palaeozoic landforms (eras within Phanerozoic eon).
Threshold
Can be either intrinsic (from within) or extrinsic (from outside).
The point at which a landform becomes unstable.
Instrinsic:
Changes within the system
e.g. surging glacier)
Extrinsic:
Changes outside of system that affect the system
e.g. formation of gullies because of progressive vegetation removal
[Dynamically] metastable states
Incremental change (trigger mechanism) pushes a system across a threshold from a stable equilibrium to a new equlibrium
Sediment budgets
The balance between sediment added to and removed from the coastal system
Surplus of sediment vs deficit of sediment
Biogeoscience
Investigates the interactions between the biological, chemical, and physical processes in life (the biosphere) with the atmosphere, hydrosphere, pedosphere, and geosphere.
Principle of simplicity (or uniformity of process)
States that no extra, fanciful, or unknown causes should be invoked if available processes will do the job.
In line with actualism (what is often confused with uniformitarianism).
Actualism v. non-actualism
Actualism = the same processes and natural laws that operated in the past are those we can actually observe or infer from observations as operating at prsent
Non-actualism = Circumstances under which processes acted in the past were very different from those experienced today, and that those differences greatly influence the interpretation of past processes.
Gradualism v. catastrophism
Gradual processes v. abrupt, major events
Steady-statism
More or less a constant state, or at least cyclical changes about a comparatively invariant mean state.
Challenges gradualism and catastrophism.
Directionalism
Directional changes
Challenges gradualism and catastrophism, as well as steady-statism.
Uniformitarianism (specific to geomorphology)
Set of beliefs about Earth surface processes and states, using actualism (uniformity of process), gradualism (uniformity of rate), and steady-statism (uniformity of state).
Opposing set of beliefs:
non-conformity of process, rate, and state
(non-actualism, catastrophism, and directionalism)
Systems approach
Examining system variables and how they interact to form a regular and connected whole.
System variables
Variables that affect a geomorphic system,
both internally and externally
e.g. internal & external variables of drainage basin
internal = soil wetness, streamflow
external = precipitation, solar radiation, tectonic uplift
Change in variables = readjustment of form and process
Isolated v. closed v. open v. dissipative systems
Isolated = completely cut off from its surroundings
*No import/export of neither matter nor energy
Closed = has boundaries
*Open to passage of energy, but not matter
Open = has boundaries
*Both energy & matter are free to move
- *Dissipative** = irreversible processes resulting in dissipation of energy
- **Energy moves one way**
(e. g. solar energy, tectonic uplift, precipitation)
Kinds of geomorphic systems (4)
- Form (AKA: Morphological) system
- Process (AKA: Cascading, Flow) system
- Form and process (AKA: Process-form, Process-response) system
- Control system
Form (morphological) systems
Sets (or systems) of form variables (or elements) deemed to interrelate in a meaningful way in terms of system origin or system function.
e.g. measures of anything on a hillslope that has size, shape, or physical properties
Process (cascading, or flow) systems
Interconnected pathways of transport of energy or matter or both, together with such storages of energy and matter as may be required.
e.g. hillslope represented as a store of materials (weathering of bedfrom and wind deposition add to the store; erosion by wind and fluvial erosion removes from the store)
Form and process (process-form, or process-response) systems
Comprise an energy-flow system linked to a form system in such a way that system processes that may alter the system form and, in turn, the changed system form alters the system processes.
e.g. rock falling off the cliff builds up the talus store; as store increases, so it begins to bury cliff face, reducing area that supplies debris –> rate of talus growth diminishes, system changes at an ever-decreasing rate (negative feedback)
Control systems
Process-form systems that interact with humans
Includes managed rivers, coasts with sea defences, some caves.
Simple systems
