The Rock Cycle5

Sedimentary Rocksfrom rock particles and fragments

Sedimentary rocks are formed over millions of years preserving evidence of past environments,

often through fossils and ripple marks.

There are two types of these rocks, one of which, clastic

sedimentary rock, is composed of the particles and fragments

of other rocks.

SandstoneSandstone is composed of fine

rocks and mineral grains. These small grains are

bonded together with smaller particles and/or calcite or silicate.

ConglomerateConglomerate is composed of a variety of larger rock fragments. These include granules, pebbles,

cobbles and boulders that are cemented together.

Mudstone and ShaleMudstones and shales are made of very

small particles of clay or silt grains that cannot be seen with the naked eye.

Shale splits readily into thin layers or sheets, whereas mudstone does not.

Limestone Limestone is composed of calcium carbonate and is formed in either of two ways;

from the shells and skeletons of organisms, such as shellfish and corals, orfrom chemicals that have precipitated out of evaporating water.

Fossiliferous limestone consists of a large number of fossils held together primarily by a calcite cement.

Major types of clastic sedimentary rocks

AS/SGRA05

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Material is washed into the sea or blown in by wind

Land

Ocean

Layers of sediment

Over time the bottom layers transform into rock

Plant and animal material decays