1. Sedimentary Rocks and Processes
Adapted from C. Block

2. Sedimentary Rocks
All of Earth history can be determined by reading the rocks

3. Much of Earth’s surface is covered in Sedimentary Rock
While most of the Earth’s crust is made of igneous rock, roughly 75% of the Earth’s surface is covered with sedimentary rock.

4. Classifying Sedimentary Rocks
Clastic Sedimentary Rocks.
Formed from the FRAGMENTS OF OTHER ROCKS
Chemical Sedimentary Rocks.
Contains usually one important mineral that has PRECIPITATED OUT from solution.
Organic Sedimentary Rocks.
Remains of ANIMALS AND PLANTS.

5. CLASTIC SEDIMENTARY ROCKS:
Most common form of sedimentary rock
Form when fragments of other rocks are cemented together

6. Formation of Clastic Rocks:
Weathering – BREAKING DOWN of existing rock into fragments by wind or motion of waves Erosion - TRANSPORT of sediment to another place by wind, water, ice, gravity.

7. Formation of Clastic Rocks
Weathering -Fragments, called sediment, is created from existing rock , transported
Deposition -Fragments settle into beds
Compaction – Sedimments get compressed
cementation - F

8. Weathering and Transport
Fragments are MOVED by wind, rivers, waves, and glaciers - running water is most common agent of movement
Particles become rounded by rubbing against each other and surroundings
The farther they travel the more rounded they become

9. Deposition
Fragments are deposited when stream slows down.

10. Compaction
Sediments are compressed by weight of overlying layers

11. Cementation
Loose sediment get stuck together when dissolved minerals settle into spaces between grains or pebbles, binding particles together.
Natural cements: silica, calcite and iron oxide.
“cement”get cemented together.
Sediments give the rocks colour:
White – silica or calcite
Red, brown, rust – form iron-based cements

12. Can sediment form rock without cement?
Yes, with enough pressure

13. Lithification Lithos – Greek word for rock
Lithification is the process of sediment compacting into rock 

15. SORTING OF SEDIMENT: Rivers and wind sort the sediment.
Fast moving rivers can carry more and larger particles.
As the river slows, because of varying steepness, it deposits the largest sediment first.

16. Sediment Clast
A CLAST is a fragment of rock or mineral, ranging in size from less than a micrometer (too small to see) to as big as an apartment block. 

17. Sorting of Sediment
Well-sorted refers to sediment clasts with particles that are approximately the same size.
Poorly-sorted sediment clasts containing particles are of many different sizes.

18. How do Sediments get Sorted?
As fragments are carried by a stream, the larger, heavier particles will settle out first.
Sediments are not always sorted into a perfect size separation: sometimes sand is found mixed with pebbles and gravel, etc and over time become cemented together. 

19. How are Sedimentary Rocks Grouped?
Sedimentary rocks are grouped according to grain size and what they are made of.

20. sdf

21. Shale
Spaces between clay particles are so tiny that water cannot pass through the rock (impermeable). 
Smooth, soft, easily broken.

22. Burgess Shale World famous fossil quarry site.
Yoho National Park, B.C.
505 million year old marine fossils. CL

23. Sandstone Rough, gritty, and durable if well cemented.
Rounded grains of quartz (< 2 mm).
Cementing minerals can include silica, calcite and hematite.
Individual grains are just visible unaided.
made from sand-sized pieces, mostly grains of quartz. 
Porous (May have up to 30% air space between grains) and therefore permeable (water is able to pass through it). 

24. Sandstone formation in Utah

25. Sandstone on Galiano Island

26. Ayers Rock, Australia CL Sandstone, bonded together with hematite.
Formed 500 million years ago, but buried for much that time.
Sand that makes up the rock eroded from an even older mountain range.

27. Monument Valley, Utah and Arizona border
Layers of sandstone eroded into the characteristic buttes of the American southwest. CL

28. Conglomerate Large and rounded pebbles and sand cemented together.
Cementing minerals can include silica, calcite and hematite.
Poorly sorted – large and small clasts within the rock.
Coarsest clastic rock

29. Breccia
Broken, angular fragments cemented together by fine-grained matrix.
Formed from debris flow deposits

30. ORGANIC SEDIMENTARY ROCKS
From the remains of once-living organisms (shells, crustaceans, and microorganisms)

31. ORGANIC SEDIMENTARY ROCKS
Eg. Limestone - made of calcium carbonate from shells fragments and coral reefs. 

32. Organic Limestone: The Sphinx and Pyramids

33. Organic Sedimentary Rocks
Eg. Coal is also made up previously living plant matter, making it organic. 

34. Chemical Sedimentary Rocks
from mineral grains that crystalize out of a solution (precipitate) by either evaporation or chemical action
Eg. Dolamite
Eg. Limestone 
Eg. Chert
Eg. Gypsum
Eg. Halite

35. Chemical Sedimentary Rocks
Eg. Limestone (also organic) 
Some limestones can also form by direct precipitation of calcium carbonate from marine or fresh water. 

36. Chemical Sedimentary Rocks
Eg. Chert is a sedimentary rock composed of quartz.
It occurs as nodules, concretionary masses, and as layered deposits. 
Chert breaks often producing very sharp edges.

37. Chemical Sedimentary Rocks
Flint
Black variety of chert.
No cleavage, but can be shaped to form sharp edges useful for tools.

38. Chemical Sedimentary Rocks
Eg. Halite (rock salt)

39. Sedimentary Features Stratification Fossils Ripple Marks Nodules
Concretions
Geodes

40. Features of Sedimentary Rocks
Stratification is the arrangement of visible layers called strata (singular, stratum)
As different sediments are laid down at different times, new rock layers may form.
Beds or layers are separated by bedding planes.

41. Stratification
What are some reasons for different sediments to be deposited?
Water slows down, depositing different size fragments, river may be diverted and then wears away different rock, weather patterns change and pick up sediments, earthquakes volcanoes may bring up different rocks.

42. Stratification

43. Features of Sedimentary Rocks
Fossils

46. Features of Sedimentary Rocks
Ripple Marks

47. Ripple Marks on Mars

48. Crossbeds in rock on Mars
Scientists could see crossbeds, in which layers of rock dip toward each other, as illustrated in this false-color image of a rock dubbed "Last Chance.

49. Features of Sedimentary Rocks
Mud Cracks
Form when water evaporates and the mud dries.
They indicate alternate drying and flooding of the area.
Usually occurs in areas which periodically dry.
Death Valley, California

50. Features of Sedimentary Rocks
Nodules
Lumps of fine-grained silica is called chert.
Concretions - round masses of calcium carbonate.

51. Features of Sedimentary Rocks
Geodes: Water dissolves some limestone forming a cavity. Then groundwater deposits quartz or calcite crystals in the cavities.
Small hollow spheres of silica rock in limestone.
Hollows may be lined with crystals of quartz or calcite.

52. Uses of Sedimentary Rock
Coal is a major energy resource
Sand and gravel for construction come from sediment.
Sandstone and limestone are used for building stone.
Rock gypsum is used to make plaster.
Limestone is used to make cement.
Salt is used for flavoring.

53. Homework Questions 10-12,14 p74-75
Limestone is a very common sedimentary rock, which is formed from previous living organisms. It contains calcite, which reacts with dilute hydrochloric acid.
Limestone is usually very well cemented, forming a hard durable surface for climbing, and is generally erosion resistant so it forms long cliff bands. That said…what do you think would happen if limestone were exposed to acid over time (perhaps from acid rain)?