Intro Flashcards
Geomorphology is the science of what?
Science of Scenery
- Study of Earth surface materials, processes and resulting landforms
- Interactions between Earth’s spheres at a variety of temporal and spacial scales
What are the spheres of interaction that geomorphology studies?
Atmosphere, Lithosphere, Hydrosphere, Cryosphere, Biosphere
What is involved in an empirical science?
Observation, measurement, description
Relevance of Geomorphology?
- Land use and planning
- Agriculture, forestry, mining, parks
- Stream/watershed management
- hydrology, flood control, water resources
Geological hazards - Volcanic hazards
- Resources for construction or mineral exploration
Geomorphology pre - 1850
- Leonardo da Vinci
- Studied topography of Arno River Northern Italy
- Drew 1st contour map of a whole river basin
- Believed rivers carved valleys and shaped topo
- Wanted to regulate river for agriculture and transport
Nicholas Steno
- Principle of original horizontality
- Law of superposition
- found shark teeth on mountains indicated SL originally higher
Law of Superposition
- Oldest at the bottom
James Hutton
- Theory of the Earth
- Uplift, erosion, consolidation of rock
- Had a lot of jobs (lawyer, chemist, physician, farming)
Sir Charles Lyell
- Uniformitarianism
- Principles of Geology in 3 volumes (1830)
- Stratigraphic principle that rock layers correlate according to fossils
- Glaciers not icebergs transport erratics
Uniformitarianism
- slow geological processes have occurred throughout history and are still occurring today
- present is the key to the past
- contrasted to accepted theory of catastrophism
Catastrophism
- theory that Earth’s features formed in a single catastrophic event and remained unchanged thereafter
- Accepted theory for a long time
- Contrasted to Lyell’s uniformitarianism
Two main geomorphic principles of Hutton and Lyell
- Landforms and landscapes evolve
- Event frequency and magnitude control landscape development
Modern Geomorphology from 1850 - 1950
- Uniformitarianism accepted but the gradualism was overstated (some events catastrophic)
- expansion of knowledge of Earth history and processes
- descriptive studies of landforms emerged (drainage basins)
Powell (1870s)
- USGS
- Colorado river exploration
- Base level of river systems
Gilbert (1878)
- Dynamic equilibrium
- Henry Mountains Utah
- Weathering, erosion, debris transport mechanisms, graded streams
- dynamic adjustment between form and process
Davis (1909), Penck (1924), King (1953)
- Cycle of Erosion
- Theories of Landscape Evolution
Cycle of Erosion
- youthful (Downcutting)
- mature (Very topographic)
- old (Eroded to bedrock, flatter)
- youthful
- Universal down-wearing to peneplain
- Increase in entropy of the system (toward equilibrium)
- uplift occurs rapidly, continuous landscape evolution through stages of erosion and decreasing slope gradients
Concept of Base Level
- The lowest elevation to which a stream can erode
- Usually coincident with sea level
Graded Stream
- over a period of years a slope is adjusted to yield the velocity required for transportation of the load supplied from the drainage basin
What were Penck and King’s contributions to the Cycle of Erosion?
- Uplift occurs gradually and continuously, not only at end of a cycle
Peneplain
final stage once base level of erosion has been reached
What was the knowledge shift in the 1950’s to present?
Shift to Process geomorphology
- Measurement based research and theory development
- Realized uniformitarianism was overstated
- understanding of processes with physics
What was the overstated uniformitarianism replaced with?
- Frequency and magnitude relations
- Equilibrium
- Thresholds
What are landforms viewed as in process geomorphology?
- Interacting Systems
- Dynamic processes of mass and energy exchange over space and time
- Landforms strive to attain equilibrium in form/function over time
- Landforms linked to larger landscape changes