Clastic Sedimentology And Petrography Quiz!

2.

Which of the following is an organic sedimentary rock?

Basalt
Conglomerate
Coal
Sandstone

Correct Answer

A. Coal

Explanation

Coal is an organic sedimentary rock because it is formed from the remains of plants that have been compacted and heated over millions of years. It is primarily composed of carbon, along with other elements such as hydrogen, oxygen, nitrogen, and sulfur. Coal is commonly used as a fuel source due to its high carbon content and ability to release energy when burned.

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3.

A rock composed of cemented, rounded pebbles is a

Porphyry
Shale
Conglomerate
Breccia

Correct Answer

A. Conglomerate

Explanation

A rock composed of cemented, rounded pebbles is called a conglomerate. Conglomerate is a sedimentary rock formed from the consolidation and lithification of gravel-sized particles. The rounded nature of the pebbles suggests that they have been transported and eroded by water before being deposited and cemented together. Conglomerate is typically found in river beds, alluvial fans, and beach environments where the transportation and deposition of large particles are common.

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4.

Ripple marks in rocks are formed by:

heating and cooling
moving wind or water
drying and shrinking
Contact with magma

Correct Answer

A. moving wind or water

Explanation

Ripple marks in rocks are formed by the movement of wind or water. When wind or water flows over loose sediment, it creates small ridges and troughs known as ripple marks. These marks are formed perpendicular to the direction of flow and are commonly found in areas such as beaches, riverbeds, and deserts. The continuous movement of wind or water causes the sediment particles to be pushed and dragged, creating these distinctive ripple patterns on the surface of the rocks.

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5.

To which of the following groups does breccia belong?

Chemical sedimentary
Clastic sedimentary
Unfoliated metamorphic
Foliated metamorphic

Correct Answer

A. Clastic sedimentary

Explanation

Breccia belongs to the group of clastic sedimentary rocks. Clastic sedimentary rocks are formed from the accumulation and lithification of fragments of pre-existing rocks or minerals. Breccia specifically is composed of angular fragments of various sizes that are cemented together. This type of rock is commonly found in areas where there has been significant tectonic activity, such as fault zones or areas of erosion and deposition.

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6.

The layering of sedimentary rock with coarse grains at the bottom and fine grains at the top is

Cross bedding
Concretion
Foliation
Graded bedding

Correct Answer

A. Graded bedding

Explanation

Graded bedding refers to the layering of sedimentary rock with coarse grains at the bottom and fine grains at the top. This phenomenon occurs when sediment is deposited in a body of water and gradually settles out, with the larger particles settling first and the smaller ones settling on top. Over time, this results in distinct layers of sediment with varying grain sizes. Graded bedding is commonly found in environments such as rivers, deltas, and deep-sea fans, where sediment is transported and deposited by water currents of varying velocities.

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7.

Scientific discipline which studies structure, origins and properties of sedimentary rocks is classified as:

Pedology
Sedimentology
Morphology
Geology

Correct Answer

A. Sedimentology

Explanation

Sedimentology is the scientific discipline that focuses on the study of the structure, origins, and properties of sedimentary rocks. It involves examining the processes of sedimentation, including how sediments are transported, deposited, and lithified to form rocks. By studying sedimentology, scientists can gain insights into past environments, climate change, and the history of the Earth. Pedology is the study of soils, morphology is the study of the form and structure of organisms, and geology is the broader study of the Earth's materials and processes. Therefore, sedimentology is the correct classification for the study of sedimentary rocks.

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8.

Sedimentary rocks can occur before sediments are made.

True
False

Correct Answer

A. False

Explanation

Sedimentary rocks are formed from the accumulation and consolidation of sediments over time. Therefore, sediments must be present before sedimentary rocks can form. Sedimentary rocks cannot occur before sediments are made, making the statement false.

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9.

Igneous rocks occur before sediments are made.

True
False

Correct Answer

A. True

Explanation

Igneous rocks are formed from the solidification of molten material, such as magma or lava. They are typically formed through volcanic activity or when magma cools and solidifies beneath the Earth's surface. Sediments, on the other hand, are formed through the weathering and erosion of pre-existing rocks. Therefore, igneous rocks are formed before sediments are made.

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10.

Fine-grained, silt-size sediment formed by the mechanical erosion of bedrock at the base and sides of a glacier by moving ice is called rock flour.

True
False

Correct Answer

A. True

Explanation

Rock flour is indeed a fine-grained sediment that is formed by the mechanical erosion of bedrock at the base and sides of a glacier by moving ice. As the glacier moves, it grinds against the bedrock, resulting in the formation of small particles of rock. These particles are then carried by the glacier and deposited in the surrounding areas. Rock flour is typically composed of silt-sized particles and has a characteristic grayish color. It is an important component of glacial landscapes and can have significant impacts on soil fertility and water quality in downstream areas.

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11.

The tendency for variations in current velocity to segregate sediments on the basis of particle size is called _____.

Lilthification
Compaction
Metamorphism
Sorting

Correct Answer

A. Sorting

Explanation

Sorting refers to the process by which sediments are separated and arranged based on their particle size. It occurs due to the tendency for variations in current velocity, such as in rivers or ocean currents, to selectively transport and deposit particles of different sizes. As the current velocity changes, larger and heavier particles settle first, followed by smaller and lighter particles. This results in the segregation of sediments into distinct layers or beds, with coarser particles at the bottom and finer particles at the top. Sorting is an important factor in sedimentary rock formation and can provide valuable information about the depositional environment.

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12.

Which of the following types of currents can transport sand grains?

Rivers
Wind
Ocean waves
All of these

Correct Answer

A. All of these

Explanation

All of these types of currents can transport sand grains. Rivers can carry sand grains downstream, wind can blow and transport sand grains through the process of erosion, and ocean waves can move and deposit sand grains along the shoreline. Therefore, all three types of currents are capable of transporting sand grains.

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13.

In which of the following sedimentary environments would you expect the sand deposits to be poorly sorted?

Alluvial
Beach
Desert
Glacial

Correct Answer

A. Glacial

Explanation

Glacial sedimentary environments are characterized by the movement of ice, which leads to the mixing of different sizes of sediment. This results in poorly sorted deposits, meaning that the sand particles are not of uniform size. The movement and melting of glaciers can cause the sand particles to be transported and deposited in a haphazard manner, leading to a lack of sorting. Therefore, in a glacial environment, the sand deposits would be expected to be poorly sorted.

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14.

Which of the following environments is an example of a shoreline/transitional environment?

Alluvial
Continental shelf
Deltaic
Organic reef

Correct Answer

A. Deltaic

Explanation

A deltaic environment is an example of a shoreline/transitional environment. Deltas are formed where a river meets a body of water, such as an ocean or a lake. They are characterized by sediment deposition and the formation of landforms such as sandbars, islands, and marshes. Deltas are transitional environments because they are located at the interface between land and water, where the river's sediment is deposited and shaped by both terrestrial and marine processes. Therefore, the deltaic environment is the correct answer.

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15.

Marine sediments deposited in water depths greater than about 12,000 feet usually lack ________

Carbonate shells
Silica-rich shells
Fine grained material transported by the wind
All of these

Correct Answer

A. Carbonate shells

Explanation

Marine sediments deposited in water depths greater than about 12,000 feet usually lack carbonate shells. This is because carbonate shells are primarily produced by organisms in shallow water environments, such as coral reefs and shallow marine habitats. As water depth increases, the conditions become less favorable for carbonate shell production, leading to a decrease in their abundance in deeper water sediments.

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Clastic Sedimentology And Petrography Quiz!

The processes responsible for changing sediments into the sedimentary rock are compaction and

Quiz Preview

Which of the following is an organic sedimentary rock?

A rock composed of cemented, rounded pebbles is a

Ripple marks in rocks are formed by:

To which of the following groups does breccia belong?

The layering of sedimentary rock with coarse grains at the bottom and fine grains at the top is

Scientific discipline which studies structure, origins and properties of sedimentary rocks is classified as:

Sedimentary rocks can occur before sediments are made.

Igneous rocks occur before sediments are made.

Fine-grained, silt-size sediment formed by the mechanical erosion of bedrock at the base and sides of a glacier by moving ice is called rock flour.

The tendency for variations in current velocity to segregate sediments on the basis of particle size is called _____.

Which of the following types of currents can transport sand grains?

In which of the following sedimentary environments would you expect the sand deposits to be poorly sorted?

Which of the following environments is an example of a shoreline/transitional environment?

Marine sediments deposited in water depths greater than about 12,000 feet usually lack ________