Geology Quiz 2 - Sedimentary Rocks

What is Lithification?

the geological process that turns loose sediment—such as sand, clay, and pebbles—into solid sedimentary rock

What does lithification involve?

• Compaction

• Dewatering

• Cementation

What is Compaction?

Reduces the amount of space between grains, packing them closer together

What is Dewatering?

Means that the water is squeezed out of the rock

What is Cementation?

Glues the grains together

What are the three types of Sedimentary Rocks?

• Clastic (detrital)

• Chemical

• Organic

What are Clastic rocks?

sedimentary rocks are made of pieces of other rock

What are Chemical rocks?

sedimentary rocks are created by a chemical process

What are Organic rocks?

o   sedimentary rocks originally come from living things

Example: Chalk

What are the Transport terminology?

• Allochthonous – moved

• Autochthonous – in place (it grew in place)

What are the Fabric terminology?

• Clasts – Rocks or fossils within a sedimentary rock (the shells within the rocks)

• Matrix – The stuff surrounding the clasts (the background around the shells)

• Matrix-supported – Clasts are suspended in clay or silt-sized particles

• Grain-supported – Particles are suspended in sand or pebbles or something larger

What are Clasts?

• Rocks or fossils within a sedimentary rock (the shells within the rocks)

What are Matrix?

• The stuff surrounding the clasts (the background around the shells)

What are Matrix-supported?

• Clasts are suspended in clay or silt-sized particles

What are Grain-supported?

• Particles are suspended in sand or pebbles or something larger

What are Chemical Sedimentary Rocks?

• Gypsum

• Limestone

• Chert (Flint)

What are Evaporite rocks?

• Gypsum

• Rock Salt

What is the “Dolomite Problem”?

10% of all sedimentary rocks are dolostone, yet dolomite is not found forming in large quantities anywhere on Earth

What is Coquina?

a limestone made almost entirely of broken shells

What is Kerogen?

a waxy oil derived from the tissue of ancient organisms

What is Coal?

is made of tree bark and other plant remains

Types of Coal - What is Lignite?

(brown coal) has the lowest amount of carbon and produces the least energy

Types of Coal - What is Bituminous Coal?

(black) burns with higher heat energy and less smoke

Types of Coal - What is Anthracite Coal?

(glassy black) is the highest grade of coal and is technically metamorphic. It burns very hot with few pollutants

What are Sedimentary structures?

are structures found in sedimentary rocks that give hints to past processes and rates

What is Planar Bedding?

horizontal layering

What is Cross-Bedding?

angled layers in horizontal sedimentary rocks formed by the migration of dunes

What are Ripples?

Essentially very small dunes (1-4 cm high) containing cross-beds

What are Mud Cracks?

rain drop prints

What are Fossils?

are traces of once living organisms