Download presentation
Presentation is loading. Please wait.
1
Section 1: Formation of Sedimentary Rocks
Sediments produced by weathering and erosion form sedimentary rocks through the process of lithification. K What I Know W What I Want to Find Out L What I Learned
2
Essential Questions How are sedimentary rocks formed?
What is the process of lithification? What are the main features of sedimentary rocks? Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
3
Vocabulary Review New texture sediment lithification cementation
bedding graded bedding cross-bedding Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
4
Weathering and Erosion
Sediments are small pieces of rock that are moved and deposited by water, wind, glaciers, and gravity. Copyright © McGraw-Hill Education Formation of Sedimentary Rocks
5
Weathering and Erosion
Chemical weathering occurs when the minerals in a rock are dissolved or otherwise chemically changed. During physical weathering, minerals remain chemically unchanged. Rock fragments break off of the solid rock along fractures or grain boundaries. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
6
Weathering and Erosion
When exposed to both chemical and physical weathering, granite eventually breaks apart and might look like this decomposed granite. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
7
Weathering and Erosion
The removal and transport of sediment is called erosion. The four main agents of erosion are wind, moving water, gravity, and glaciers. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
8
Weathering and Erosion
After rock fragments and sediments have been weathered out of the rock, they often are transported to new locations through erosion. Eroded material is almost always carried downhill. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
9
Weathering and Erosion
Deposition Deposition occurs when transported sediments are deposited on the ground or sink to the bottom of a body of water, forming layers with the largest grains of sediment at the bottom. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
10
Weathering and Erosion
Energy of transporting agents As moving water slows down, some sediment deposits are sorted into layers of different-sized particles. The largest particles settle out first, then the next largest, and so on. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
11
Weathering and Erosion
Energy of transporting agents Wind can move only small grains, so sediment deposits made by wind are usually fine and well-sorted. Some sediment deposits contain particles of all sizes because they are dumped in unsorted piles when, for example, a glacier melts or there is a landslide. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
12
Lithification As more sediment is deposited in an area, the bottom layers are subjected to increasing pressure and temperature. These conditions cause lithification, the physical and chemical processes that transform sediments into sedimentary rocks. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
13
Lithification Compaction
Lithification begins with compaction. The weight of overlying sediments forces the sediment grains closer together, causing physical changes. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
14
Lithification Cementation
Cementation occurs when dissolved minerals precipitate out of groundwater and their growth glues sediment grains together into solid rock. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
15
Sedimentary Features Bedding
The primary feature of sedimentary rock is horizontal layering called bedding, which results from the way sediment settles out of water or wind. Bedding in which the particle sizes become progressively heavier and coarser toward the bottom layers is called graded bedding. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
16
Sedimentary Features Bedding
Cross-bedding is formed as inclined layers of sediment are deposited across a horizontal surface. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
17
Sedimentary Features Ripple marks
When sediment is moved into small ridges by wind or wave action or by a river current, ripple marks form. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
18
Visualizing Cross-Bedding and Ripple Marks
Moving water and loose sediment result in the formation of sedimentary structures such as cross-bedding and ripple marks. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
19
Add link to Animation from p. 139 here.
Visualizing Cross-Bedding and Ripple Marks Concepts In Motion FPO Add link to Animation from p. 139 here. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
20
Sedimentary Features Angular vs. rounded
As sediment is transported, pieces that began with an angular shape knock into each other and become rounded as their edges are broken off. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
21
Sedimentary Features Evidence of past life
Fossils are the preserved remains, impressions, or any other evidence of once-living organisms. During lithification, parts of an organism can be replaced by minerals and turned into rock, such as shells that have been mineralized. Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
22
Review Essential Questions Vocabulary
How are sedimentary rocks formed? What is the process of lithification? What are the main features of sedimentary rocks? Vocabulary sediment lithification cementation bedding graded bedding cross-bedding Formation of Sedimentary Rocks Copyright © McGraw-Hill Education
Similar presentations
