Sedimentary key knowledge

• What is a rock type created on river floodplains?

  Mudstone or siltstone
• What Is the coal series (lowest rank to highest)?

  Peat, Lignite, Bituminous coal, Anthracite
• Why are fluvial sediments less well sorted than aeolian sediments?

  Fluvial sediments are transported for shorter distances
• Argillaceous, rock with laminations?

  Shale
• Name three sedimentary structures found in a turbidite.

  Flute clasts , graded bedding and cross bedding
• What structure forms when wet sediment dries and contracts due to water evaporation?

  Desiccation cracks
• What theory maintains that the same earth processes at work today have occurred throughout geological time?

  Uniformitarianism
• What produces a flute clast?

  Turbidity flow
• Rock type found in wadi channels.

  Breccia or conglomerates
• Limited erosion in a fluvial environment results in what dominant grain shape?

  Sub rounded to sub angular
• The only common material not affected by chemical weathering.

  Quartz
• Rock made of calcium carbonate and containing ooliths.

  Oolitic limestone
• A coarsening upwards sequence can often indicate what environment?

  Delta
• What does sorting mean?

  The variation of grain sizes within a sediment
• Well sorted and rounded grains of quartz, arenaceous, quartz cement.

  Orthoquartzite
• Minerals precipitate from predators around edges of the grains to bind the cement together.

  Cementation
• What mineral does hydrolysis mainly affect?

  Feldspars
• Why does a fining upwards sequence occur in a turbidite?

  Decreasing energy as turbidity flow hits the abyssal plain
• What's exfoliation weathering?

  Large temperature variation between day and night cause expansion and contraction of the rock. It peels apart in layers
• Sedimentary rock found in alluvial fan?

  Breccia nearest mountains, arose further away
• Term for clay particles clumping together and therefore becoming large enough to deposit.

  Flocculation
• Ripple marks produced by bidirectional current.

  Symmetrical
• Rudaceous rocks:

  • Over 50% of clasts are <2mm in diameter
  • Primarily consists of rock fragments
  • If particles rounded = conglomerate, angular particles = breccia
• Arenaceous rocks:

  • Over 50% of particles are 1/16 to 2mm in diameter
  • Comprise of a high quartz grains %
  • Generally sandstones
  • Wide variety: desert sandstone, arkose, greywacke, orthoquartzite
• Argillaceous rocks:

  • Over 50% of particles are <1/16mm in diameter
  • Consists of clay minerals and small quartz grains
  • Rock types are siltstone, mudstone, clay and shale