SEDIMENTARY ENVIRONMENTS

• sedimentary environment - part of the earth’s surface, physically, chemically, and biologically distinct from adjacent terrain
• facies - mass of sedimentary rock which can be defined and distinguished from another by its geometry, lithology, sedimentary structure, paleocurrent

  patterns, and fossils
• LITHOLOGY - texture, mineralogy, sorting, shape
• GEOMETRY - due to geomorphology and pre- and post-depositional history
• sedimentary structures - are formed by the deposition of sedimentary materials, such as sand, gravel, and pebbles
• FOSSILS

  assumptions:

  • fossils lived where it was buried
  • habitat is deduced by the fossil morphology
• TERRESTRIAL

  • alluvial fans
  • fluvial (rivers)
  • lacustrine (lakes)
  • paludal (marsh and swamps)
  • aeolian (desert)
  • glacial
• TRANSITIONAL

  • delta
  • beach
  • lagoon
  • tidal flats
• MARINE

  • reef
  • continental margin (slope, shelf, rise)
  • abyssal plain
• alluvial fan - a fan-shaped deposit of material carried by a river
• alluvium - sediment deposited by a river in a valley
• fluvial - the river is the main agent of transportation, and the river is the main agent of deposition
• meandering rivers - consists of a single channel and a thalweg (deepest point in a channel)
• braided river - consists of multiple bars and thalwegs within a single low sinuosity channel; poorly sorted, coarse-sediments
• anastomosing river channels - multiple, interconnected, coexisting channel belts on alluvial plains
• straight river channel - more of a hypothetical end member of river channels and not often found in nature
• drainage patterns - area where surface water from rain/snow/ ice converges to a single point at a lower elevation
• dendritic drainage pattern - resembles branches
• Trellis drainage pattern - alternating resistance layer
• Radial drainage pattern – volcanic domes, domal uplifts
• centripetal drainage pattern - central depression/basin
• rectangular drainage pattern - faulted, fracture igneous rock
• deranged drainage pattern - scattered
• lacustrine/lakes - land-locked body of standing water usually formed as a result of water filling depressions
• paludal - marshlands and swamps; constant flooding of water, organic material, and fine sediments
• aeolian/eolian - ability of the wind to shape the surface of the Earth (and other planets) by erosion, transportation, and deposition
• DEFLATION - removal of loose particle by the wind
• ABRASION - cannonading of rock and other surfaces by particles carried by the wind
• desert - generally formed in areas with little to no rain (<250 mm/year)
• FORMATION OF DESERT - by-product of global atmospheric circulation
• SEDIMENT EROSION

  • ventifacts
  • lag deposits
• SEDIMENT DEPOSITS

  • desert pavement
  • loess
  • sand dunes
• TYPE OF SAND DUNES

  • barchan dunes – crescent-shaped, unidirectional wind direction
  • parabolic
  • traverse dunes
  • linear/ longitudinal
  • star dunes
• glacial - permanent (on a human scale) body of ice that shows evidence

  of movement due to gravitational pull
• GLACIAL DRIFT - sediment deposited as result of glacial erosion
• transitional environment:

  • part land, part ocean
  • delta
  • lagoon
  • tidal flats
  • beach
• delta - formed when rivers empty into larger bodies of water (lakes, sea, and/ or ocean)
• types of delta are characterized by dominant erosive agent

  • river-dominated
  • tide-dominated
  • wave-dominated
• RIVER-DOMINATED

  • significant sediment input from rivers
  • protrudes into the sea
  • lobate in shape (moderate sediment supply)
  • bird’s foot shape (large sediment supply)
• TIDE-DOMINATED

  • linear features parallel to tidal flow and perpendicular to the shore
  • ocean “eats away” and progresses into the land creating a triangular-shaped mouth