Clastic sedimentary rocks are classified based on grain size into conglomerate, sandstone, siltstone, shale and mudstone. Conglomerates contain rounded gravel size clasts (>2mm) in a finer matrix. They form from erosion of other rocks. Sandstones contain quartz and feldspar grains between 0.06-2mm. Shales and mudstones have the finest grains (<0.06mm) composed of clay minerals and quartz silt. Shales are fissile while mudstones are non-fissile. Clastic rocks form from weathering and erosion of older rocks transported by rivers, glaciers, wind or ocean currents.

1. Classification
of
Clastic Sedimentary
Rock

2. *formed from broken rock fragments weathered
and eroded by river, glacier, wind and sea
waves. These clastic sediments are found
deposited on floodplains, beaches, in desert
and on the sea floors.
CLASTIC ROCKS
Clastic rockssolidify
• Clastic rocks are classified on the basis of
the grain size: conglomerate, sandstone,
shale etc.

3. *Clastic rocks
mainly comprise
broken fragment of
older rock – they
are also know as
Terrigenous rocks
Clastic Rock:-
Clastic Process-

4. RUDACEOUS
Rock
ARENACEOUS
Rock
ARGILLACEOUS
Rock

5. •RUDACEOUS ROCKS:-
•These include all coarse grained clastic rock of heterogeneousThese include all coarse grained clastic rock of heterogeneous
composition.composition.
•Made up of rounded or sub-rounded Pebbles - cobbles
(Conglomerate) and angular to subangular Pebbles -
cobbles ( breccia ) .
•Example-
1.Conglomerate
2.Breccia

6. It is consist rounded fragments of various sizes, but generally
above 2 mm.
 Conglomerate rock is aConglomerate rock is a
common sedimentary rock.common sedimentary rock.
 Conglomerate is aConglomerate is a
sedimentary rock formedsedimentary rock formed
from rounded gravel andfrom rounded gravel and
boulder sized clasts moreboulder sized clasts more
than 30% by volumethan 30% by volume
cemented together in acemented together in a
matrix.matrix.
• Rounded clasts.Rounded clasts.
• Unique clast composition.Unique clast composition.
• Uniform clast-size.Uniform clast-size.
• Chaotic clast orientation.Chaotic clast orientation.

7. ConglomerateConglomerate
(A) (B)

8. (A) Extraformational Conglomerate:-(A) Extraformational Conglomerate:-
Clasts derived from aClasts derived from a
distant source.distant source.
A conglomerate in which clasts areA conglomerate in which clasts are
exotic (i.e., derived from outside theexotic (i.e., derived from outside the
depositional basin). Clasts aredepositional basin). Clasts are
normally very well rounded and wellnormally very well rounded and well
sorted as they have been transportedsorted as they have been transported
for larger distance.for larger distance.
1.OrthoConglomerate:-:-
conglomerates may have no matrix between clasts (openconglomerates may have no matrix between clasts (open
framework) or spaces between clasts may be filled by lessframework) or spaces between clasts may be filled by less
than 15 % matrix of finer sediment (closed framework).than 15 % matrix of finer sediment (closed framework).
2.ParaConglomerate:-conglomerateconglomerate
in which most clasts are not in contact; i.e., thein which most clasts are not in contact; i.e., the
matrix supports the clasts which is more than 15%matrix supports the clasts which is more than 15%

9. Oligomictic conglomerate :-Oligomictic conglomerate :-
A conglomerate in which the clasts are made up ofA conglomerate in which the clasts are made up of
only one rock type.only one rock type.
Suggests that the source area was nearbySuggests that the source area was nearby
and have one or similar source rock.and have one or similar source rock.
Polymictic conglomerate :-Polymictic conglomerate :-
Conglomerates that include clastsConglomerates that include clasts
from a wide-variety of source rocks,from a wide-variety of source rocks,
possibly derived over a widepossibly derived over a wide
geographical area or a smaller butgeographical area or a smaller but
geologically complex areageologically complex area..

10. (B) Intraformational conglomerate :-(B) Intraformational conglomerate :-
A conglomerate in whichA conglomerate in which
clasts are derived locallyclasts are derived locally
from within thefrom within the
depositional basin (e.g.,depositional basin (e.g.,
clasts composed of localclasts composed of local
muds torn up by currents;muds torn up by currents;
such clasts are commonlysuch clasts are commonly
termed "rip-up clasts" ortermed "rip-up clasts" or
"mud clasts")."mud clasts").
A conglomerate in whichA conglomerate in which
clasts are derived locallyclasts are derived locally
from within thefrom within the
depositional basin (e.g.,depositional basin (e.g.,
clasts composed of localclasts composed of local
muds torn up by currents;muds torn up by currents;
such clasts are commonlysuch clasts are commonly
termed "rip-up clasts" ortermed "rip-up clasts" or
"mud clasts")."mud clasts").
Deposition in anDeposition in an
environment whereenvironment where
muds accumulated.muds accumulated.
Muds were in veryMuds were in very
close proximity to theclose proximity to the
site of deposition assite of deposition as
the clasts would notthe clasts would not
withstand considerablewithstand considerable
transport.transport.
Deposition in anDeposition in an
environment whereenvironment where
muds accumulated.muds accumulated.
Muds were in veryMuds were in very
close proximity to theclose proximity to the
site of deposition assite of deposition as
the clasts would notthe clasts would not
withstand considerablewithstand considerable
transport.transport.

11. If grains are rounded, the rock is
termed as ‘Breccia’
• GRAIN SIZE-2mm to several cm, in finer
matrix

12. volcanismtectonism
weathering
Meteoric
impact

13. ARGILLACEOUS ROCKS:-
Made up of clay size sediments. This is fine grained rock
and grain size 1/250mm to 1/64mm.
Example-
1. Shale
2. Mudstone
3. Claystone

14. *Shales are clastic rocks, made
up mainly fine silt/clay
*They are most abundant
sedimentary rocks, accounts
for about 80% of them
*Often contain fossils
*Mostly hydrous aluminum
silicate in composition = from
weathered feldspars
• Shales are made of fine well sorted silt and clayey sediments,
where normally one can expect high porosity and
permeability.
Shale= Quartz
+ feldspar + mica
Rock Type Sediment Grain Size
Shale Clay less than
0.001
mm
Shale

15. Three type on the basis of their Origin-
1.Residual Shales
2.Transported Shales
3.Hybrid Shales

16. • A grey or black rock formed from
mud, mudstones contain both
detrital minerals, such as quartz
and feldspar, and clay minerals and
carbonaceous matter. Individual
grains, however, are too small to
be seen without a hand lens. Some
mudstones are fossiliferous, others
are calcareous and react with acid.
• GRAIN SIZE-Less than 0.1mm.
• ESSENTIAL COMPONENTS-Quartz,
feldspar.
• GRAIN SIZE-Less than 0.1mm.
• ESSENTIAL COMPONENTS-Quartz,
feldspar.
Grey mudstone inNamibia

17. • Clay is typically dark to light grey but a pure white variety
called china clay can occur. Individual grains may be seen
only under powerful microscopes.
• GRAIN SIZE - Less than 0.005mm.
 ESSENTIAL COMPONENTS - Clay minerals, such as
kaolinite, illite

18. •ARENACEOUS ROCKS:-
• Made up of mainly sand e.g. Sandstone. These rocks
are either accumulated by wind action or deposited
under water action or marine to non marine. This rock is
medium grained and grain size is 1/16mm to 2mm.
•Example-
1.Sandstone
2.Silt stone
3.Arkose
4.Greywacke
5.Grit
This rock other name is Terrigenous.

19. Sandstone:-
 One of the most common sedimentary rocks, sandstone
is usually quartz-dominated with visible sandy grains.
 One of the most common sedimentary rocks, sandstone
is usually quartz-dominated with visible sandy grains.
• GRAIN SIZE-0.1–2mm.
 ESSENTIAL COMPONENTS-Quartz,
feldspar.
 ADDITIONAL COMPONENTS-Mica
and many others.

20. Classification of Sand StoneClassification of Sand Stone
Silica (SiO3) is cementing materialSilica (SiO3) is cementing material
In cementing material is CaCO3
& Mg
In cementing material is CaCO3
& Mg
Cementing material is clayey in
character
Cementing material is clayey in
character
Cementing material is fe
composition
Cementing material is fe
composition

21. Siltstone:-
 GRAIN SIZE 0.1–2mm.
 ESSENTIAL COMPONENTS-Quartz, feldspar.
 ADDITIONAL COMPONENTS-Mica and many
others.
 Siltstone is another detrital sedimentary rock, lying
in grain size between sandstone and mudstone.
Like sandstone, it can form in different
environments and have different colours and
textures, but reds and greys, and planar bedding are
typical. Plant fossils and other carbonaceous matter
are common in darker-coloured siltstones. The
presence of mica may produce a flaggy siltstone.
 Siltstone is another detrital sedimentary rock, lying
in grain size between sandstone and mudstone.
Like sandstone, it can form in different
environments and have different colours and
textures, but reds and greys, and planar bedding are
typical. Plant fossils and other carbonaceous matter
are common in darker-coloured siltstones. The
presence of mica may produce a flaggy siltstone.

22. A pink sandstone, the colour of which is due to an abundance of
feldspar, especially pink alkali feldspars.Arkose forms by the fast
deposition of sand weathered from granites and gneisses
GRAIN SIZE= 0.1–2mm.
ESSENTIAL COMPONENTS- Feldspar, quartz.
A pink sandstone, the colour of which is due to an abundance of
feldspar, especially pink alkali feldspars.Arkose forms by the fast
deposition of sand weathered from granites and gneisses
GRAIN SIZE= 0.1–2mm.
ESSENTIAL COMPONENTS- Feldspar, quartz.

23. • Greywacke has formed from a mixture of sand and, proportionately
less, mud. It is a dark-coloured rock( grey, dark green, or black)
containing .
• Poorly sorted angular fragments of quartz and basic igneous rock
and fine grained chlorite or clay material.
• Greywacke's may contain as much as 30% fine grained clay or
chlorite or both.
• GRAIN SIZE 0.005–2mm.
• ESSENTIAL COMPONENTS-
Rock and mineral fragments.

24. Grit or Grit stone:-
Grit is a hard,coarse grained rock , siliceous
sandstone.
It is a sandstone containing sharply angular grain that
May rub off easily.
Most grit are formed in water.
Grit is a hard,coarse grained rock , siliceous
sandstone.
It is a sandstone containing sharply angular grain that
May rub off easily.
Most grit are formed in water.
The chief mineral components
are quartz , feldspar and mica.
The chief mineral components
are quartz , feldspar and mica.
This term is especially applied
to such sandstone that are
Quarried for building material.
This term is especially applied
to such sandstone that are
Quarried for building material.