Sedimentary rocks (2)

Sedimentary Rocks
A Virtual Practical
I.G.Kenyon


The following slides are all
sedimentary rocks
From the information displayed
Decide if the rock is:
clastic, organic or chemical
Identify each rock
accurately as possible
Suggest a sedimentary environment
in which it may have formed

as


Identify this Sedimentary Rock 1
1cm

Poorly Sorted

40% Muddy Matrix

Rock Fragments

Mineral Grains


Identify this Sedimentary Rock 2

Reacts with dilute
hydrochloric acid

Comprises over 70%
broken bivalve shells

Remainder of rock is
silt and iron oxides
2cm


Identify this Sedimentary Rock 3
2cm

Comprises entirely clay minerals and carbonaceous material
Well preserved graptolites are found in the rock
Splits into thin layers easily (Fissile)


Identify this Sedimentary Rock 4
1cm

Reacts with dilute hydrochloric acid
Comprises entirely of spherical grains 0.5–1.0mm in diameter


Identify this Sedimentary Rock 5
Made up entirely
of clay minerals

such as kaolinite,
illite and bentonite

Homogenous or
massive with no
trace of bedding
or laminations

1cm


Identify this Sedimentary Rock 6
4cm

Comprises angular fragments 0.5mm – 8cm in diameter
All parts of the rock react with dilute hydrochloric acid


Identify this Sedimentary Rock 7

5mm

Comprises mainly sub angular quartz and feldspar grains
20% of the rock has fragments 2 - 4mm in diameter


Identify this Sedimentary Rock 8
Fibrous appearance

Very low density

Clearly visible remains
of organic matter

Rich in carbon
1cm


Identify this Sedimentary Rock 9
2cm

Composed entirely of silica
Broken surfaces show conchoidal fracture


Identify this Sedimentary Rock 10
1cm

Comprises some clay minerals such as kaolinite and illite
Has a gritty feel when rubbed on the teeth, >10% quartz present


Identify this Sedimentary Rock 11

Well rounded flint pebbles 8mm – 6cm in diameter
Cement does not react with dilute hydrochloric acid


Identify this Sedimentary Rock 12
1cm

Rich in carbon, makes a black mark on paper
No recognisable traces of organic material evident


Identify this Sedimentary Rock 13
1cm

Grain size <1/256mm

Comprises almost entirely clay minerals, chiefly kaolinite
No bedding or laminations evident. Plastic when wet


Identify this Sedimentary Rock 14
1cm

Comprises well rounded quartz grains 0.25 – 0.5mm in diameter
Weak iron oxide cement-crumbles in the fingers (friable)


Identify this Sedimentary Rock 15
2cm

Fossil replaced
by flint

Reacts with dilute hydrochloric acid
Rock is made up of coccoliths

Identify this Sedimentary Rock 16

1cm

Reacts with dilute hydrochloric acid
Made up mainly of broken crinoid stems


Identify this Sedimentary Rock 17
1cm

Comprises entirely well rounded quartz grains 0.25–0.75mm in diameter
Very well cemented together by silica


Identify this Sedimentary Rock 18

1cm

Reacts with dilute hydrochloric acid
Comprises angular fragments 0.5mm – 5cm in diameter


Identify this Sedimentary Rock 19
Comprises angular to
sub angular grains of
quartz and feldspar

Contains more than

25% feldspar

Iron oxide cement
1cm


Identify this Sedimentary Rock 20
Particle size varies
from 1mm – 4cm

Comprises fragments of
limestone, basalt, slate
and quartz

All particles are angular

Red iron oxide cement

1cm


Identify this Sedimentary Rock 21

1cm

Comprises quartz and muscovite grains
Splits readily into slabs 3-6cm thick


Identify this Sedimentary Rock 22

1cm

Reacts with dilute hydrochloic acid
Made up entirely of angular shell fragments 0.5-3mm


Identify this Sedimentary Rock 23
Has a woody ‘ring’
to it when tapped

Rich in carbon

Low density

1cm
1cm

Organic structure
clearly visible