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Sedimentary rocks Formed in seas and lakes. Formation  Rock materials  Derived from weathering and erosion  Are transported by river / wind  And later.

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Presentation on theme: "Sedimentary rocks Formed in seas and lakes. Formation  Rock materials  Derived from weathering and erosion  Are transported by river / wind  And later."— Presentation transcript:

1 Sedimentary rocks Formed in seas and lakes

2 Formation  Rock materials  Derived from weathering and erosion  Are transported by river / wind  And later deposited (sedimentation)  Under the pressure of the overlying sediment  These materials are hardened into solid rock

3 Characteristics of sedimentary rocks  Non-crystalline  Stratified (layered)  Bedding planes between rock strata  May contain fossil

4 Conglomerate

5 Characteristics  Rock containing rounded pebbles  they are cemented by fine groundmass  It is more resistant  Their outcrop across stream beds may produce waterfalls and rapids

6 Breccia

7 Characteristics  The rock contains angular fragments

8 Breccia – Ap Chau

9 Folding in sedimentary rocks

10

11 Ammonite fossil

12 Sandstone

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14 Characteristics  Sand grains are cemented  Deposited farther away from the coast  Less resistant than conglomerate and breccia

15 Siltstone

16 Stratification in shale e.g.Tung Ping Chau

17 Siltstone layer being eroded to form a sea arch, Tai O.

18 Characteristics  Very fine sediment of silt and mud is deposited and cemented together on sea floor far away from coast  Made up of numerous thin layers (stratified structure)  It is not resistant to weathering and erosion

19 Cross-bedding in siltstone

20 Faulting in siltstone

21 Igneous rocks - Volcanic rocks Ash, pyroclasts and lava flows

22 Flowlines in rhyolite

23 Columnar jointing due to cooling of lava - rhyolite

24

25 Coarse tuff

26 Characteristics  Ash and pyroclastic materials ejected during volcanic eruption  Presence of volcanic bombs

27 Volcanic bombs

28 Igneous rocks - Hypabyssal rocks In sills and dykes

29 Dolerite dyke

30 Dolerite

31 Feldspar porphyry

32

33 Igneous rocks In batholith

34 3 sets of joints in granite

35 Granite

36 Badland landscape


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