Sedimentary Rocks and Fossil Dating

Study Notes

Study of the distribution of fossils in sedimentary rocks to understand the geological history of an area
Uses fossils to date and correlate rock layers
Based on the principle of faunal succession, which states that fossils found in rock layers can be used to determine their relative age
Important in reconstructing the geological history of an area, including its paleoenvironment, paleoclimate, and tectonic evolution

A sedimentary facies is a body of sediment that has a unique set of characteristics, such as composition, texture, and fossil content
Reflects the depositional environment in which the sediment formed, such as a river delta, ocean basin, or desert
Can be used to reconstruct the paleoenvironment and depositional history of an area
Sedimentary facies can be further divided into:
- Lithofacies: the physical characteristics of the sediment, such as its composition and texture
- Biofacies: the fossil content of the sediment
- Chemical facies: the chemical composition of the sediment

The physical characteristics of a sedimentary rock, such as its:
- Composition (e.g. sandstone, shale, limestone)
- Texture (e.g. grain size, sorting, sedimentary structures)
- Color
- Hardness
Can be used to infer the depositional environment and conditions under which the sediment formed
Important in understanding the geological history of an area and reconstructing the paleoenvironment

A bedding plane is a surface that separates two distinct layers of sedimentary rock
Forms when sediment is deposited in a new layer on top of an existing layer
Can be used to:
- Identify individual beds or layers of sedimentary rock
- Determine the orientation and sequence of sedimentary layers
- Analyze the depositional history and paleoenvironment of an area

The process of converting sediment into sedimentary rock
Involves:
- Compaction: the compression of sediment due to overlying weight
- Cementation: the precipitation of minerals from solution to fill pore spaces
- Replacement: the replacement of original minerals with new ones
- Recrystallization: the growth of new minerals from original ones
Important in understanding the formation and characteristics of sedimentary rocks
Can affect the texture, composition, and fossil content of sedimentary rocks

Study of fossils in sedimentary rocks to understand geological history of an area
Uses fossils to date and correlate rock layers
Based on principle of faunal succession: fossils in rock layers determine relative age
Essential in reconstructing paleoenvironment, paleoclimate, and tectonic evolution

A sedimentary facies is a body of sediment with unique characteristics
Characteristics include composition, texture, and fossil content
Reflects depositional environment: river delta, ocean basin, or desert
Used to reconstruct paleoenvironment and depositional history
Divided into:
- Lithofacies: physical characteristics
- Biofacies: fossil content
- Chemical facies: chemical composition

Physical characteristics of sedimentary rock
Characteristics include composition, texture, color, and hardness
Used to infer depositional environment and conditions
Essential in understanding geological history and reconstructing paleoenvironment

Surface separating two distinct layers of sedimentary rock
Forms when sediment is deposited in a new layer
Used to:
- Identify individual beds or layers
- Determine orientation and sequence of sedimentary layers
- Analyze depositional history and paleoenvironment