Clastic and Biochemical Sedimentary Rocks (class notes)

clastic (Detrital)

made up of clasts, 5 steps: weathering, erosion, transportation, depostition, Lithification,

biochemical (Organic)

Limestone, chalk, chert, coal, made of dead organisms remains, made from shells,

clasts

a fragment of rocks of various sizes

Lithification

transformation of loose sediment into solid rock

Mudrock/ shale

made of mostly silt or clay sized clasts(to small to see), form in quite water, most abundant sedimentary rock, make slopes

siltstone

slightly bigger clasts than shale but still too small to see

Sandstode

made of sand sized particles, quartz is most abundant mineral,

quartz

hardness of 7, very resistant to weathering, makes up most of sand

well sorted

grains all similar sizes, transported by wind or water

poorly sorted

grains different sizes, transported by glaciers or gravity, conglomerate and brecca

rounded grains

longer transportation, probably water or sand,

shells

made mostly from calcite, and sometimes from silica

diatomite

made up of the microscopic shells of diatoms that accumulate and do not undergo recrystallization

coal

made from organic carbon that is the remains of fossil plant matter