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Rocks B. Sedimentary Rocks.

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Presentation on theme: "Rocks B. Sedimentary Rocks."— Presentation transcript:

1 Rocks B. Sedimentary Rocks

2 What are sedimentary rocks formed from?
Where do sedimentary rocks form? How do you turn sediment into rock?

3 Sedimentary rocks are formed from sediments

4 What are sediments? When the process called weathering attacks rocks near or at the surface, the rocks are broken into fragments. This fragmentary material is called sediment. Sediments come in different shapes and sizes: Boulders Silt Pebbles mud Gravel clay Sand

5 Depositional Environments for Sediments or
Where sediments are deposited after they are transported

6 Where sediments accumulate:
a- alluvial fans h-deltas b- Glaciers i- tidal flats c- rivers j- continental shelf d- dunes k-continental slope e- lakes L-abyss f- lagoons m-reefs g- estuaries There are three major deposition settings: continental, marginal marine, and marine

7 How do sediments become Sedimentary Rocks?
form by the lithification of unconsolidated sediments. lithification is a process of compaction and cementation

8 What sediments produce what rocks?
Sandstone Mudstone Siltstone Shale Conglomerate Breccia Sediment Sand Mud Silt Clay Rounded gravel Angular gravel These are called Detrital sedimentary rocks: because they are made of detritus or solid particles of other rocks


10 Chemical Sedimentary Rocks
Sometimes material is dissolved in water as the rocks are weathered. This material is transported to lakes and oceans where it can reform into minerals and rocks by: inorganic chemical reactions or the activities of organisms (organic). these are often called biochemical sedimentary rocks

11 Chemical sedimentary Rocks (inorganic)
Sometimes when water evaporates, the dissolved chemical precipitate out minerals. e.g. Rock salt ( NaCl ) Rock Gypsum ( CaSO4.2H2O ) Chert (SiO2) is a hard rock is is made of microscopic crystals of quartz. (can also be bio-chemical) It comes in several colored varieties flint (Black) jasper (brown/red) novaculite (white) agate (banded)

12 Rock gypsum Chert Coal Rock salt Chemical Sedimentary Rocks

13 Bio-Chemical sedimentary Rocks (organic)
These are formed by living organisms Chert can be made from the accumulations of silica shells Coal is formed from woody land plant material Limestone (fossilifereous) ( CaCO3) is formed from the accumulation of seashells Limestone (chalk) ( CaCO3) is formed from the accumulation of microscopic shells

14 Bio-chemical Sedimentary Rocks
Limestone (fossiliferous) Limestone (chalk)

15 Some common Sedimentary Rocks you will have to learn.
Sandstone* Limestone (chalk) Conglomerate* Siltstone Breccia* Shale* Mudstone* Chert* Coal* Rock Salt Limestone (fossiliferous)* * = must know for test

16 Sedimentary Structures: Crossbedding
= desert sand dune

17 Sedimentary Structures:Ripple marks
= streams, lake shores

18 Sedimentary Structures: Fossils
= environment, age, comparison


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