The rock type, texture, grain size, composition, and other comments on the sedimentary rocks is shown... Sediment is a material that is occurred naturally and broken down by processes of physical or chemical weathering, and erosion. Physical weathering like: Frost wedging, Unloading, Thermal Expansion and Biological activity. Chemical weathering like: Dissolution, Hydrolysis and Oxidation. Weathering rates are a function of the rock type, slope (topography), structure, and the prevailing climate. Rocks that are most resistant are composed of minerals that are relatively unaffected by chemical weathering like: Quartz (that are more resistant than any other rock types). Sediments are transported by the action of wind, ice (glaciers), the gravity force acting on particles and most of them by water. Sediments can be classified based on their composition and grain size which is a good indicator of the energy or force required to move a grain of a given size.

1. Soran University
Faculty of Engineering
Petroleum engineering department
Sedimentary Rocks
Prepared by : Raboon Redar Supervised by : Mr. Arkan
Mansur Nidhal
2019

2. Sedimentisamaterial thatisoccured naturallyandbrokendownbyprocessesof physical orchemical weathering,and
erosion.Physical weatheringlike:Frostwedging,Unloading,ThermalExpansionandBiological activity.Chemical
weatheringlike:Dissolution,HydrolysisandOxidation.Weatheringtendstoroundoff cornersandleave thingsmore
smoothinshape that iscalled"Spheroidal weathering".Weatheringattacksthe rock'sface onone side,edgesontwo
side andthe corner on three sides(makesthemroundedorspherical).Thatmeansroundedrocksare veryweathered
unlike angularrockswhicharen'tmuch weathered.Weatheringratesare a functionof the rock type,slope (topography),
structure,andthe prevailingclimate.Rocksthatare mostresistantare composedof mineralsthatare relatively
unaffectedbychemical weatheringlike:Quartz(thatare more resistantthanany otherrock types).
Sedimentsare transportedbythe actionof wind,ice (glaciers),the gravityforce actingonparticlesandmostof themby
water.Sedimentscanbe classifiedbasedontheircompositionandgrainsize whichisa goodindicatorof the energyor
force requiredtomove a grainof a givensize.
- Large sedimentssuchasgravel,cobbles,andbouldersrequire more energytomove thansmallersand,silt,andclay
sizedsediments.
- Grain size isalsoan indicatorof the distance or lengthof time the sedimentsmayhave traveled.Smallergrainsizes
generallyindicate greatertransportdistancesanddurationthanlarger grains.
• Gravel ≥ 2 mm
• Sand– 2 mmto 1/16 mm
• Silt– 1/16 mm to 1/256 mm
• Clay≤ 1/256 mm
Mineral compositionreferstothe specificmineralsinthe rock.e.g.Sandstone will containpredominantlyquartz,while
limestonewillcontainmainlycalcite(calciumcarbonate).
Detrital sedimentaryrocks:Itmay be an accumulationof material thatoriginatesandistransportedassolidparticles
derivedfrombothmechanical andchemical weathering.These depositsare termeddetrital,andthe rockstheyformare
calleddetrital sedimentaryrocks.Some examplesof clasticsedimentaryrocks:Shale,Mudstone,Siltstone,Sandstone,
Arkose,Graywacke,Conglomerate andBrecia

3. Rock name Rock type Texture Grain size Composition Comments
Chert Biochemical
Fine to
clastic
Microcrystalline
Mainly
quartz
(SiO2)
is a hard
Chalk Clastic - Calcite
Is soft,
white
Breccia Detrital Course Over 2mm -
Broken
fragment
Conglomerate Detrital Course Over 2mm -
Color: tan
to brown
Dolomitised
limestone
Chemical Non-clastic -
Calcite
(CaCo3)
They share
same color
ranges of
white-to-
gray and
white-to-
light brown
Gypsum Chemical
Fine to
course
Non-clastic
-
Gypsum
(CaSO4)
Is a soft
Sandstone Detrital Course Over 2mm -
May be any
due to
impurities
within the
minerals
Coal Chemical Non-clastic - -
Color:
black or
brownish-
black
Fossiliferous
limestone
Biochemical Clastic -
Calcite
(CaCo3)
Color: light
to medium
gray

4. Shale Detrital Very fine
Less than
1/256mm
-
Color :
dark to
grey
References
Anon.,n.d. wikipedia. [Online]
Available at:https://en.m.wikipedia.org/wiki/sediment
CharlesC.Plummer,D.H. C. ,.L. H., n.d.In: PhysicalGeology. FifteenthEditioned.s.l.:MCGRAWHILL EDUCATION,pp.
128-129.
Jain,S.,n.d.In: Fundamentalsof PhysicalGeology. s.l.:Springer,pp.131-145.