Geology Practical Week 5

Mudstones

Lithified clays and silts made up grains

rich in feldspar and quartz

coarse = consists of silt (bumpy)

fine = clay (feels waxy)

Biogenic and chemical sedimentary rocks

sedimentary rocks consists of preexisting rocks and minerals

fossils, shells, chemical precipitates, organic matter

limestone

most common non-clastic sedimentary rock

aka

clastic sedimentary rocks

conglomerate - coarse (grainy)

sandstone - medium (sand-sized particles)

mudstone - fine (cannot see w naked eye)

non-clastic sedimentary rocks

formed by chemical precipitation or organic/biochemical accumulation rather than by fragments of pre-existing rocks

not originating from mechanical weathering or transported fragments

ex; limestone, rock salt, gypsum, coal

proximity to sediment source

closer to source = coarse

mid-way = medium

farther from source = fine-grained

conglomerates

found in high energy environments such as rivers, alluvial fans, glacial deposits, and coastal areas

Grain size classification

calcirudite - very coarse

calcarenite - medium

calcilutite - very fine