Week 6: Sedimentary Rocks flashcards

These flashcards cover key vocabulary and concepts from the lecture on sedimentary rocks, suitable for exam preparation.

Clastic rock formation

The process involving five steps: weathering, erosion, transportation, deposition, and lithification.

Weathering

A combination of processes that break up and corrode solid rock, subdivided into physical and chemical weathering.

Physical weathering

Weathering involving natural processes such as jointing, exfoliation, and root wedging.

Chemical weathering

The process where rocks are broken down by chemical reactions, such as dissolution or hydrolysis.

Biological agents

Organisms like plant roots, fungi, and bacteria that facilitate weathering by producing organic acids.

Erosion

The separation of detritus from their original substrate by agents such as wind, water, ice, and gravity.

Transportation in geology

The movement of eroded clasts away from their original locations due to the medium’s velocity and viscosity.

Deposition

The process that occurs when detritus settles out of the transporting medium.

Lithification

The transformation of loose detritus into solid rock through compaction and cementation.

Clastic sedimentary rocks

Rocks formed from clasts that are cemented together.

Biochemical sedimentary rocks

Rocks made from shells or organic materials, such as limestone formed from shell debris.

Organic sedimentary rocks

Rocks made of organic carbon from the remains of living organisms, like coal and oil shale.

Chemical sedimentary rocks

Rocks formed when minerals precipitate from solution.

Grain size classification

Classification of clastic rocks based on the size of their clasts (e.g., boulders, cobbles, pebbles, sand, silt, mud).

Sorting

The uniformity of grain size in sedimentary rocks; well-sorted rocks have similar-sized grains.

Stratigraphy

The study of the layers (strata) of sedimentary rocks and their relationships.

Transgression and Regression

Transgression is the shorelines' inward migration due to rising sea levels; regression is the outward migration due to falling sea levels.

Turbidity currents

Submarine flows where sediment and water rapidly move downslope, often leading to the deposition of graded beds.

Sedimentary structures

Features formed during the deposition of sediments including layers, bedding, impressions, and cross-bedding.

Lithification process

A two-step process involving compaction and cementation that transforms sediment into sedimentary rock.