1. Sedimentary Rocks

2. Sedimentary rocks form when sediment is compacted or cemented into solid rock
Figure 3.2 Sedimentary layers of sandstone form steep cliffs above the San Juan River in Utah.
Fig. 3-2, p.46

3. The Rock Cycle

4. Weathering Sediment becomes smaller, more rounded and more sorted
silicate minerals react with water to form clay (a new solid mineral) and dissolved ions (quartz is the exception)
Weathering agents: water (most important), wind, gravity, glaciers

5. Rock Cycle Processes - Lithification

6. Lithification: Turning sediment into sedimentary rock
Compaction : wet, buried sediment is squeezed by overlying sediments, causing it to become more solid.
Cementation minerals dissolved during the weathering process precipitate and act as a cement, e.g. calcite, silica, and iron oxide.

7. Sedimentary Rock Classification Based on sediment source
Detrital Sedimentary Rocks
Chemical Sedimentary Rocks
Biochemical Sedimentary Rocks
Organic Chemical Sedimentary Rocks

9. Detrital Sedimentary Rocks
composed of solid sediment from weathered rocks
conglomerate, sandstone, shale

10. Chemical Sedimentary Rocks
Calcite
CaCO3

11. Bio-

12. Chemical Sedimentary Rocks
Composed of minerals precipitated from surface or ground water (chemical sediment)
rock salt, rock gypsum
Includes biochemical Sedimentary Rocks, composed of sediment of biological origin (e.g. shell fragments)
Most common example is rock salt.

13. Organic sedimentary rocks
Coal
Different from other rocks because it is composed of organic material
Stages in coal formation (in order)
1. Plant material
2. Peat
3. Lignite
4. Bituminous Coal
5. Anthracite (metamorphic)

14. Figure 6.13a,b

15. Figure 6.13b,c

16. Figure 6.13c,d

17. Sedimentary environments
Sedimentary rocks contain evidence of past environments
They provide information about climate (sediment size, presence or absence of water, sea level)
Often contain fossils, which are indicators of both past climates and possible presence of fossil fuel.

18. Sedimentary environments
Sedimentary environment or environment of deposition: A geographic setting where sediment is accumulating
Determines the nature of the sediments that accumulate (grain size, grain shape, and other properties.)
Today’s sedimentary rocks, tell us about past environments of deposition

19. Figure 6.5

20. Continental Sedimentary Environments
Dominated by erosion and deposition associated with
Streams
Wind (eolian sandstones)

21. Continental Sedimentary Environments
Glacial (morainal material)
Alluvial fans (arkosic, feldspar-rich materials)

22. Shallow Marine Sedimentary Environments

23. Deep Marine Sedimentary Environments

24. Transitional Sedimentary Environments
Tidal flats
Lagoons
Deltas

25. Sedimentary structures
Provide information useful in the interpretation of Earth’s history
Types of sedimentary structures
Strata, or beds (most characteristic of sedimentary rocks)
Cross-bedding
Ripple marks
Mud cracks

26. Figure 6.17

27. Figure 6.18a

28. Figure 6.18b

29. Figure 6.21a

30. Figure 6.21b