1. Sedimentary Rocks
A sedimentary rock is formed by the accumulation and compaction of sediments (rock pieces, minerals, animal parts, or chemical precipitates)

2. Sediments are derived from weathering of rocks
Chemical weathering – Dissolution or decomposition of minerals grains due to chemical reactions

3. Bowen’s Reaction Series: The last minerals to crystallize are the most resistant to weathering.
Susceptible to weathering
Resistant to weathering

4. Mechanical weathering – Breakage of rock due to cracking, scratching, crushing, freezing, thawing, and abrasion

5. There are 3 different types of sediments
Detrital (clastic) sediments – Pieces of eroded rock fragments and minerals grains. Sediments of this type form Detrital Sedimentary Rocks

6. There are 3 different types of sediments
Detrital (clastic) sediments – Pieces of eroded rock fragments and minerals grains. Sediments of this type form Detrital Sedimentary Rocks
Chemical sediments – Minerals precipitated from water due to chemical reactions (ex. calcite, gypsum, halite). These sediments form Chemical Sedimentary Rocks

7. There are 3 different types of sediments
Detrital (clastic) sediments – Pieces of eroded rock fragments and minerals grains. Sediments of this type form Detrital Sedimentary Rocks
Chemical sediments – Minerals precipitated from water due to chemical reactions (ex. calcite, gypsum, halite). These sediments form Chemical Sedimentary Rocks
Biochemical sediments – Mineral remains of organisms or minerals precipitated due to biological processes (ex. shells, plant fragments, carbon). Sediments of this type form Biochemical Sedimentary Rocks

8. Detrital sedimentary rocks are classified according to their grain characteristics:
Size of the grains: refers to the range of sizes of the individual sediment pieces found within the rock. Can be divided into three categories:
coarse-grained
Boulder, cobble, pebble, granule
medium-grained
Sand
fine-grained
Silt, clay

9. Classification of Clastic Sedimentary Rocks based on grain sizes
Category: Coarse Medium Fine
Sediment: Boulder | Cobble | Pebble | Sand | Silt | Clay
Size (mm):
Rock Name: Conglomerate Sandstone Siltstone Shale
Conglomerate
Sandstone
Shale

10. Grain shape refers to the roundness of the minerals
Grain shape refers to the roundness of the minerals. Grains that are well-rounded indicate they have traveled a long distance
Angular Rounded Well-Rounded

11. Grain sorting refers to the amount of similar size pieces within a sample
Well-Sorted
Poorly-Sorted

12. Chemical and Biochemical sedimentary rocks are classified by their chemical composition
Common chemical sedimentary rocks include:
Crystalline Limestone (calcite = CaCO3)

13. Chert (quartz = SiO2)
Rock Salt (halite = NaCl)

14. Common biochemical sedimentary rocks include:
Rock Gypsum (gypsum = CaSO4 · 2H3O)
Common biochemical sedimentary rocks include:
Fossiliferous Limestone
(well cemented calcite body parts)

15. Coquina
(poorly cemented calcite shells)
Bituminous Coal (Carbon compounds from partially decayed plant matter)

16. A depositional environment is any place where sedimentary rocks form
Environments can be characterized as high, medium or low energy

17. The larger the pieces being moved, the higher the energy of the environment
Mountain river, alluvial fan = high energy
Swamp, deep ocean = low energy
The more the pieces are being moved about, the higher the energy of the environment
Swash zone of beach = high energy
Floodplain, playa lake = low energy

18. Sedimentary structures are features preserved in rocks that give information about the depositional environment.
Common examples include:
(a) cross-beds,

19. (b) ripples, and
(c) bioturbation