Geography 323 -- Geomorphology

Geological Basis of Geomorphology

  1. Active role of the geological framework: endogenic processes
  2. Passive role of the geological framework: resistance to exogenic processes

Endogenic Processes

isotope half-life (yrs)
U238 4.5 x 109
U235 7.1 x 108
Th232 1.4 x 1010
K40 1.3 x 109

Plate Tectonics

  1. constructive: plates moving apart; molten rock injected adding new rock to the trailing edge of the plates and creating ridges, mostly on the floors of ocean basins
  2. destructive: collision or, more commonly, subduction of denser oceanic plates below margins of less dense continental plates, creating oceanic trenches and mountain belts on the continental margins
  3. conservative: transform faults where plates slide past one another (e.g. San Andreas fault)

Diastrophism (Gr: dia (across), strophe (turn))

  1. Orogenesis (Gr. oros: mountain)
  2. Epeirogenesis (Gr. epeiros: continent)


Types of Volcanic Activity
  1. exhalative: gas
  2. effusive: lava
  3. explosive: ash or tephra
[ Course Outline | Next Topic ]