1. Sedimentary Rocks
A Virtual Practical
I.G.Kenyon

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

3. Identify this Sedimentary Rock 1
1cm
Poorly Sorted
40% Muddy Matrix
Rock Fragments
Mineral Grains

4. 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

5. 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)

6. Identify this Sedimentary Rock 4
1cm
Reacts with dilute hydrochloric acid
Comprises entirely of spherical grains 0.5–1.0mm in diameter

7. 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

8. Identify this Sedimentary Rock 6
4cm
Comprises angular fragments 0.5mm – 8cm in diameter
All parts of the rock react with dilute hydrochloric acid

9. Identify this Sedimentary Rock 7
5mm
Comprises mainly sub angular quartz and feldspar grains
20% of the rock has fragments 2 - 4mm in diameter

10. Identify this Sedimentary Rock 8
Fibrous appearance
Very low density
Clearly visible remains of organic matter
Rich in carbon
1cm

11. Identify this Sedimentary Rock 9
2cm
Composed entirely of silica
Broken surfaces show conchoidal fracture

12. 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

13. Identify this Sedimentary Rock 11
Well rounded flint pebbles 8mm – 6cm in diameter
Cement does not react with dilute hydrochloric acid

14. Identify this Sedimentary Rock 12
1cm
Rich in carbon, makes a black mark on paper
No recognisable traces of organic material evident

15. 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

16. 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)

17. Identify this Sedimentary Rock 15
Fossil replaced by flint
2cm
Reacts with dilute hydrochloric acid
Rock is made up of coccoliths

18. Identify this Sedimentary Rock 16
1cm
Reacts with dilute hydrochloric acid
Made up mainly of broken crinoid stems

19. Identify this Sedimentary Rock 17
1cm
Comprises entirely well rounded quartz grains 0.25–0.75mm in diameter
Very well cemented together by silica

20. Identify this Sedimentary Rock 18
1cm
Reacts with dilute hydrochloric acid
Comprises angular fragments 0.5mm – 5cm in diameter

21. Identify this Sedimentary Rock 19
Comprises angular to sub angular grains of quartz and feldspar
Contains more than 25% feldspar
Iron oxide cement
1cm

22. 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

23. Identify this Sedimentary Rock 21
1cm
Comprises quartz and muscovite grains
Splits readily into slabs 3-6cm thick

24. Identify this Sedimentary Rock 22
1cm
Reacts with dilute hydrochloic acid
Made up entirely of angular shell fragments 0.5-3mm

25. Identify this Sedimentary Rock 23
Has a woody ‘ring’ to it when tapped
Rich in carbon
Low density
Organic structure clearly visible
1cm
1cm

26. Identify this Sedimentary Rock 24
2cm
Made up entirely of hydrated calcium sulphate
This variety is called Desert Rose

27. Identify this Sedimentary Rock 25
Mica flakes concentrated on lamination surfaces
1cm
Contains some clay minerals, chiefly kaolinite
Over 10% quartz present plus mica flakes
Feels gritty when rubbed on the teeth

28. Identify this Sedimentary Rock 26
Jet black colour
Contains over 95% carbon
Vitreous lustre
Marks paper
No recognisable traces of any organic matter
1cm

29. Identify this Sedimentary Rock 27
2cm
Made up entirely of clay minerals, chiefly kaolinite
No obvious laminations or bedding present
Contains well preserved trilobite pygydium

30. Identify this Sedimentary Rock 28
2cm
2cm
Reacts with dilute hydrochloric acid
Has an internal concentric banded structure
Specimen obtained from the roof of a limestone cave

31. Identify this Sedimentary Rock 29
Majority of clasts are rounded to well rounded
Poorly sorted, grain size varies <1mm to 10cm

32. Identify this Sedimentary Rock 30
Composed entirely of sodium chloride
Occurs in thin, near horizontal beds
Often grey, white colourless, orange or brown
Tastes salty
1cm

33. Identify this Sedimentary Rock 31
1cm
All parts of the rock react with dilute hydrochloric acid
Comprises shell fragments, faecal pellets and large ooliths

34. Identify this Sedimentary Rock 32
1cm
Comprised of clay minerals and carbonaceous material
Lacks distinct laminations
Contains well preserved plant fragment

35. Identify this Sedimentary Rock 33
1cm
Comprises mainly quartz grains <0.25 in diameter
Brown colour due to 10-15% clay content
Contains external moulds and casts of brachiopods

36. Identify this Sedimentary Rock 34
Contains a high percentage of sub-rounded to rounded quartz grains
Some rock fragments
Poorly sorted, particle size ranges from <0.5mm – 1cm
Finer matrix makes up 15-20% of the rock
No reaction with dilute hydrochloric acid
1cm

37. Identify this Sedimentary Rock 35
1cm
Rich in iron, hence brownish colour (limonite)
Cannot be found forming anywhere on earth today

38. Name this Sedimentary Rock 36
Reacts with dilute hydrochloric acid Contains corals preserved in life position

39. Identify this Sedimentary Rock 37
Locally known as Haggis Rock
1cm
Sub-angular to sub-rounded particles
Mixture of rock fragments and quartz grains 0.5mm to 5mm in diameter
Matrix consists of mud and silt and makes up over 20% of the rock

40. Identify this Sedimentary Rock 38
1cm
Particle size 1mm up to 8mm, quite poorly sorted
Mineralogy mainly sub-angular to sub-rounded quartz and feldspar

41. Identify this Sedimentary Rock 39
1cm
Reacts with dilute hydrochloric acid May contain a small percentage of clay minerals

42. Identify this Sedimentary Rock 40
1cm
Comprises quartz grains 0.25 – 0.75mm in diameter
Moderately well cemented by glauconite, a pale green mineral

43. Answers 1. 1. Greywacke 11. Conglomerate
2. Bioclastic Limestone Bituminous Coal
3. Black Shale Clay
4. Oolitic Limestone Desert Sandstone
5. Mudstone Chalk
6. Limestone Breccia Crinoidal Limestone
7. Millstone Grit Orthoquartzite
8. Peat Limestone Breccia
9. Flint Arkose
10. Siltstone Breccia

44. Answers 2. 21. Micaceous Sandstone 31. Biochemical Lst.
22. Calcareous sandstone Mudstone
23. Lignite(Brown Coal) Fine Sandstone
24. Rock Gypsum Conglomerate
25. Micaceous Siltstone Ironstone
26. Anthracite Coral Limestone
27. Mudstone Greywacke
28. Tufa Grit
29. Conglomerate Micrite/Marl
30. Rock Salt Orthoquartzite

45. The End