II. Sedimentary Rock – Rocks formed from sediment
They are grouped by their formation and are considered
either clastic or nonclastic.
A. Clastic – formed when sediment is compacted and
compressed over time into solid rock.
* Clastic rock is grouped by the size of the sediment
involved (see below)
Large 1. Gravel – forms Conglomerate or Breccia
(rounded sediment) (angular sed)
2. Sand – forms Sandstone
3. Silt – forms Siltstone
Small 4. Clay – forms Shale – has flat layers that split
Color and type of rock is determined by the color and
type the mineral within.
Ex. Red sandstone and white sandstone
 Sediment sizes can combine to form different rocks
Ex. Silty sandstone or sandy siltstone
(Sedimentary rocks continued)
B. Nonclastic – not formed through the clasitc method
Two nonclastic methods.
1. Chemical – one of two ways
a. precipitation- minerals precipitate (settle out) of
water and form rock
Ex. Chemically formed limestone- calcite from
seashells precipitate out of water when it cools in the
ocean.
b. Evaporation – when water evaporates out of a
mineral solution leaving the mineral behind
Ex. Rock salt - when halite and gypsum are left
behind
Ex. Stalactites and Stalagmites (calcite) form this
way in caves
2. Organic – Rock formed from the remains of living
things.
Ex. Coal – formed from buried and compressed plant
remains
Ex. Limestone – formed form the compaction of shells
(calcite form animals such as clams and oysters
Chalk – white form of limestone
II. Sedimentary Rock – Rocks formed from sediment
They are grouped by their formation and are considered
either clastic or nonclastic.
C. Clastic – formed when sediment is compacted and
compressed over time into solid rock.
* Clastic rock is grouped by the size of the sediment
involved (see below)
Large 1. Gravel –
2. Sand –
3. Silt –
Small 4. Clay –
Color and type of rock is determined by the color and
type the mineral within.
Ex.
 Sediment sizes can combine to form different rocks
Ex.
(Sedimentary rocks continued)
D. Nonclastic – not formed through the clasitc method
Two nonclastic methods.
1. Chemical – one of two ways
a. precipitation- minerals precipitate (settle out) of
water and form rock
Ex.
b. Evaporation – when water evaporates out of a
mineral solution leaving the mineral behind
Ex.
Ex.
2. Organic –
Ex.
Ex.