Presentation is loading. Please wait.

Presentation is loading. Please wait.

Rock Identification Modified from a PowerPoint presentation prepared by J. Crelling, Southern Illinois University.

Similar presentations


Presentation on theme: "Rock Identification Modified from a PowerPoint presentation prepared by J. Crelling, Southern Illinois University."— Presentation transcript:

1 Rock Identification Modified from a PowerPoint presentation prepared by J. Crelling, Southern Illinois University

2 Characterizing Rocks There are 3 major types of rocks IGNEOUS – formed from molten magma SEDIMENTARY – formed from sediment (soil, sand, etc,) METAMORPHIC – formed by applying heat and pressure to other existing rocks

3 The Rock Cycle – a representation of the interrelationship between different types of rocks.

4 Characterizing Rocks The three major characterizing features of rocks are: Color Color Composition (Mineralogy/Chemistry) Composition (Mineralogy/Chemistry) Texture Texture Note: Even the most sophisticated geological classification schemes are based on these features

5 Characterizing Rocks Classification by Color Color Index (used mainly for igneous rocks) Leucocratic – light color Leucocratic – light color Mesocratic – intermediate color Mesocratic – intermediate color Melanocratic – dark color Melanocratic – dark colorand/or Felsic – rich in light colored minerals Felsic – rich in light colored minerals Mafic – rich in dark colored minerals Mafic – rich in dark colored minerals

6 Igneous Rocks Textures of Igneous Rocks Aphanitic – fine-grained. Individual grains can’t be seen with naked eye Aphanitic – fine-grained. Individual grains can’t be seen with naked eye Phaneritic - grains easily seen with the naked eyePhaneritic - grains easily seen with the naked eye Porphyritic – larger grains in finer grains InclusionsPorphyritic – larger grains in finer grains Inclusions > Xenoliths > Xenoliths > Xenocrysts

7

8

9

10 Vesicular & Glassy Textures

11 Xenoliths

12 Xenocryst

13

14

15 Sedimentary Rocks Detrital & Chemical Rock Classification Detrital RocksChemical Rocks ConglomerateLimestone SandstonesChert (Flint) SiltstoneSalt (Evaporite) Shale

16 Detrital Sedimentary Rocks Detrital rocks are classified based on particle size and grain shape

17 Detrital Sedimentary Rocks Conglomerates Conglomerates –Poorly Sorted particle sizes –Well-rounded particles –Usually particles are gravel sized

18

19

20

21 Detrital Sedimentary Rocks Breccia Breccia –Poorly sorted grains –Angular grains –Gravel sized grains

22

23

24 Detrital Sedimentary Rocks Sandstone Sandstone – Well sorted particles – Particles can be angular to rounded – Sand-sized Particles

25

26

27 Detrital Sedimentary Rocks Shale Shale – Microscopic grain size – Consist of silt and clay size grains – Cannot see grains with naked eye – Occur in “quiet” depositional environments

28

29

30 Chemical Sedimentary Rocks Classification Classification – Inorganic - Not produced by living things. – Biochemical - Are produced by or are remnants of living things (e.g. shell fragments, coral reefs, etc)

31 Chemical Sedimentary Rocks Limestone Limestone – Most abundant chemical rock – Inorganic (oolitic limestone, Travertine) or Biochemical (Chalk, Coquina)

32 Limestone (Chemical Rocks) Travertine Travertine – Common in caves – Happen when calcium carbonate is precipitated out of groundwater

33 Limestone (Chemical Rocks) Coquina Coquina – Consists of loosely cemented shell fragments

34 Fossiliferous limestone Limestone

35 Fine-grained limestone

36 Chemical Sedimentary Rocks Chert (Flint) Chert (Flint) – Consists of Microcrystalline Silica – Two major occurrences of chert Irregular shaped nodules in limestone Irregular shaped nodules in limestone layers of rock layers of rock – Most likely Biochemical

37 Cross-section through a geoid showing silica layering

38 Flint

39

40 Metamorphic Rocks Classified into two main groups Classified into two main groups – Foliated Rocks – Non-foliated Rocks

41

42 Foliated Rocks Progression of Shale to Gneiss Progression of Shale to Gneiss – SlateLow Metamorphic Grade – Phyllite – Schist – GneissHigh Metamorphic Grade Metamorphic Rocks

43 Foliated Textures Slaty - very fine-grained, fissile Slaty - very fine-grained, fissile Phyllitic - fine-grained, foliated, shinny Phyllitic - fine-grained, foliated, shinny Schistose - foliated, large grains visible Schistose - foliated, large grains visible Gneissic - light and dark bands Gneissic - light and dark bands Metamorphic Rocks

44 Slate Parent Rock Parent Rock – Shale Slaty Cleavage Slaty Cleavage

45 Phyllite Parent Rock – Slate Characteristic sheen/shine Phyllitic Texture

46 Schist Parent Rock Parent Rock – Phyllite Characteristic scaly appearance Characteristic scaly appearance Schistosity Schistosity

47 Gneiss Parent Rock Parent Rock – Schist Characteristic of light and dark banding Characteristic of light and dark banding Gneissic Texture Gneissic Texture

48 Non-foliated Rocks Rocks that show no Foliation Rocks that show no Foliation – Crystalline Rocks – Marble – Quartzite – Anthracite (coal) Metamorphic Rocks

49 Marble Parent Rock Parent Rock – Limestone or Dolostone Reacts to Acid Reacts to Acid

50

51 Quartzite Parent Rock Parent Rock – Sandstone Moderate to high metamorphism Moderate to high metamorphism Very Hard Very Hard

52 Anthracite (coal) Parent material Parent material – Plant matter High metamorphism High metamorphism Shinny and hard Shinny and hard

53


Download ppt "Rock Identification Modified from a PowerPoint presentation prepared by J. Crelling, Southern Illinois University."

Similar presentations


Ads by Google