Sedimentary rocks Flashcards
what are depositional environments
where sediments get left
what are sediments
preweathered material
what are the factors characterising depositional environments
types of transporting agent, type and composition of sediment, flow characteristics of transporting agent, site of deposition and types and abundance of organisms
what is ithification
the process of transforming sediment into sedimentary rock. this is done but piles of sediment being compacting and minerals precipitating throughout the sediment
what are the main types of sedimentary rocks
clastic, volcaniclastic, biogenic, organic and chemical
what are clastic rocks made out of
made of clasts which are pieces of minerals or pre-existing rock formed through weathering
what are volcaniclastic rocks made out of
clastic with a large part of those clasts have volcanic origin
what are biogenic rocks made out of
made of particles originally produced by living organisms
what are organic rocks made out of
made of compressed and heated plant material
what are chemical rocks made out of
made from precipitated dissolved particles
what is the relationship between the energy of the transporting medium and clast size
the energy determines the size of clasts the medium can transport, further away energy dissipates and clast size reduces
what are the characteristics of conglomerates
contains clasts greater than 2mm that are rounded
what are the characteristics of breccia
contains clasts greater than 2mm that are angular
what are the characteristics of sandstone
contain clasts ranging from 2-0.25mm, feels gritty and can see with naked eye
what are the characteristics of siltsone
contains clasts ranging from 0.063-0.004mm feels smooth
what are the characteristics of claystone
contains clasts smaller than 0.004mm, feels smooth
what are the characteristics of Mudstone/shale
contains clasts 0.063-0.25mm, feels smooth breaks into blocks where the shale is fissle/ splits easily into thin parallel layers
what are the characteristics of limestone
biogenic sedimentary rock, composed primarily of calcium carbonate
what are the characteristics of chalk
biogenic sedimentary rock, very fine grained limestone
what are the characteristics of coal
biogenic sedimentary rock, forms from plant debris which accumulates in swampy environments
what are the characteristics of evaporites
chemical sedimentary rock, forms from evaporation of mineral rich water
what is bedding in sedimentary rocks
layers of rocks with differences with the layers above and below formed during the lithification process, defined by changes in grain size, composition and/or colour. upper and lower layers are known as bedding planes
what do sedimentary rocks mean in relation to engineering
hard to generalize due to with range of lithologies and structures so thorough site investigation is needed
