erosion and digenesis

• Grain shape is described in terms of roundness: Very Angular, angular, sub-angular, sub-rounded, rounded, well-rounded.
• Shape is dictated by how long a grain has been transported for, the further they are carried the rounder/smaller they become.
• Clay is too small to be affected greatly by erosion in transport.
• Physical and chemical Properties of mineral grains that influence grain size and shape: Hardness, Cleavage, The reactivity with water.
• Sorting is the degree to which the grains are sorted, a well sorted grain means the grains are all the same size, poorly sorted means there is a wider range of grain sizes.
• River sediment is poorly sorted in the upper courses, moderate in the middle/lower courses.
• Glacier sediment is very poorly sorted.
• Beach sediment is moderately to well sorted.
• Sand dune sediment is very well sorted.
• Texture: Size - energy, Shape - length of transport, Sorting - environment.
• Things that cause a drop in energy and then deposition are: Less rainfall, Inside a meander bend, Lower gradient, River flowing into another body of water, A river confluence, Water fall.
• Quartz and muscovite mica dominate coarser particles because quartz is unreactive with high hardness and no cleavage, Mica is ductile and rolls up instead of breaking.
• To deposit a substance dissolved in solution the solute needs to evaporate.
• Single grains of clay can only be deposited In still water, clay can stick together in clumps due to a process called flocculation, This happens with increasing salt content.
• Porosity = volume of voids in sediment/total volume of sediment x 100
• Permeabiltiy is the ability of a rock/sediment to allow fluid to travel through it.