Question 1         The term "shale" includes what size classes?           Answers:   It includes the silt and clay classes

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It includes the silt and clay classes.

It is strictly limited to silt sized particles.

It is strictly limited to clay sized particles.

It is a general term that refers to sand and silt mixtures.

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1/16th mm to 1/256 mm

anything less than 1/256th mm

1/16mm to 1/10 mm

1/1000mm to 1/5000 mm

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It refers to fragments that are produced by some abrasion process like rocks being transported in a stream.

It is associated with sediments that settle to the bottom of a stream or other body of water.

It is a process in which the minerals in a sedimentary rock were formed through hydrothermal solutions.

It is an indication of the age of the minerals that make up the rock, detrital being older than chemical.

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It is the degree of separation of grain sizes in a sediment.

It is the separation of one mineral type by currents.

It refers to what type (or sort) of fluid is responsible for the movement of the sediments. It could be by wind, water or ice.

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They have not been transported very far from where they were formed.

They consist of very hard rocks that do not become more rounded very easily.

They are constantly being formed and then fragmented again. It is due to the fact that they are found along active fault zones.

Commonly they are very porous and as a result acidic solutions permeate the rocks and etch them to produce the sharp edges that make it angular.

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It relates to the distance of transport. The more angular the fragments the shorter the distance of transport.

It is a observation of what types of minerals make up the fragments in the rock. Quartz is a very hard mineral and would therefore expected to be an angular fragment.

It is related to the packing of the grains in the sediment or in the sedimentary rock. If the grains are very angular they will not compact very easily.

The angularity of a detrital grain is dependent on how the grain was created. Very angular grains are produced by large earth movements, as along fault zones. Less angular particles are produced by things like stream abrasion.

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Calcite Cement

Silica Cement

Lithification was accomplished simply by pressure.

This unusual breccia was cemented by gypsum.

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Chrysocolla

Copper

Azurite

Malachite

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They are areas where fluids can deposit important ore minerals.

There importance lies in their danger. The zones of brecciation signify rocks that can move easily and pose a danger to people and mining equipment.

Because the brecciated zones are weakly held together, they are easy to excavate. This means more rock can be moved in a short amount of time.

Brecciated zones are an indicator of copper minerals.

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After sediments are deposited, the sediments are ripped up and redeposited in the same area.

Different sedimentary formations are broken and fragments from each accumulate to form this rock type.

Once the conglomerate is formed it is later exposed at the surface. It then erodes and pieces of it produce a new conglomerate.

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Conglomerates consist of rounded grains; breccia grains are angular.

Conglomerates can form in beach or river environments, whereas breccias are always found along fault zones.

Conglomerates are formed at the surface of the Earth while breccias are produced deep below the surface.

Breccias are coarser grained than conglomerates.

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It is physically and chemically stable at the Earth's surface.

It is the most common mineral found in the rocks at the Earth's surface so their is an over abundance of it in sedimentary environments.

Quartz actually grows in areas where sand accumulates. So as sand sized particles accumulate, quartz grows along with them.

It is actually semantic. In order for a sedimentary rock to be called a sandstone it must contain quartz as its dominant mineral.

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Iron oxides coat each of the quartz grains.

The color is caused from near by rocks and soils. Groundwater transports the mineral dyes from surrounding rocks to color the often colorless surrounding rocks, including sandstone.

It is age related. Oxygen causes a chemical reaction on the surface of quartz grains. A new sandstone will be very light in color but as it ages it yellows. Continued exposure to oxygen darkens it to brown and then finally a deep reddish brown.

The color is caused by other minerals in the sandstone. Most commonly the coloring mineral is garnet, which can create all of these colors (and more).

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This is any sediment derived from erosion on land.

Terrigenous refers to those rocks on Earth (aka Terra) as opposed to that small fraction of rocks that are derived from space.

Terrigenous sediments are those that are derived exclusively from the processes of stream erosion.

The term is used to describe mineral grains that are dark in color. These are usually rich in iron and magnesium.

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It consists of clay which is derived by the weather of feldspars. Feldspars are the most common mineral making up the crust of the Earth.

Shale is the densest of the sedimentary rocks. When it forms it resists uplift and erosion.

Shales are commonly silicified. That means that when they form their pore spaces are completely filled with silica, which is a very durable material. So shale tends to accumulate.

When a sediment lithifies into a shale a chemical reaction takes place that bonds each mineral grain covalently to the adjacent grains. This bond is very difficult to break. The shale is therefore very resistant to erosion and it accumulates in great quantities.

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It is a shale that shows many fine bedding layers caused by the accumulation of clay.

It is a shale that breaks easily.

It is a shale that when struck with a hammer, cleaves like mica.

It is a shale that is so very dense that it breaks with a conchoidal cleavage.

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It has to do with the energy of the environment where each sediment is deposited. Shales accumulate in quiet (low turbulence) areas. An organic object simply settles to the bottom where the shale particles are accumulating. The organic object is then buried in tact. When the sediments are lithified a well formed fossil is created. On the other hand, conglomerates are high energy deposits. They form where lost of currents or waves are found. An organic particle does not do well in an area where pebbles and boulders are abrading together.

Shales protect potential fossils from scavengers. Very often shales contain hydrogen sulfide or other toxic gases that prevent scavengers from disturbing the organic remains. Conglomerates are formed closer to the surface where oxygen is abundant. Scavengers have no problem in having their way with the organic remains.

Shales are an immense storage area for fossils because they are so durable at the Earth's surface. Once a fossil forms in a shale it will persist for hundreds of millions of years. Conglomerates are poorly cemented and can be broken down easily. This process destroys any fossils that it may have contained.

It has to do with the size of the grains. Because shales are so fine grained they can preserve even microscopic fossils. These tiny fossils are preserved in very large numbers. Conglomerates are so coarse grained that a potential fossil would have to be extremely large. So things like dinosaur bones or petrified wood are found in conglomerates, but not much else.

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A leaf fossil

An amoeba fossil

A fossil jellyfish

The inner ear bone of a walrus

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compositon

grain size

color

specific gravity

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Limestone

Shale

Gypsum

Diatomite

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It is often used as trophy bases.

It is used as a mild abrasive.

Its primary use is in conditioning acidic soils.

It is used as a pigment in paints.

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Limestone

Shale

Salt

Chert

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These are changes that take place after a sediment is deposited but before it is lithified.

These are changes that take place after a sedimentary rock is formed. A diagenetic change would be something like folding or faulting.

Diagenetic is very superficial. It would be a change in the color of the rock without any change in composition.

Groundwater passing through the rock can dissolve some of the more soluble minerals. The removal of these grains produces a diagenetic rock.

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It is a small clam that lives in the surf zone.

It is a one celled animal that creates a calcite shell.

A coquina refers to any of the shelled invertebrates that contribute to the buildup of limestone on the ocean floor.

Coquina is a coral animal responsible for the creation of coral reefs.

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Chalk

Flint

Sandstone

Diatomaceous Earth

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Through the action of groundwater replacing the Ca in calcite with Mg.

Dolomites are created when limestones are metamorphosed.

Dolomites are created when limestones are diagenetically enriched with silica.

The formation of a dolomite involves the recrystallization of calcite to form a different crystal structure that is more stable under higher pressures. This new structure is of the mineral dolomite.

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Quartz

Calcite

Gypsum

Halite

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Chert

Coal

Shale

Gypsum

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They are used to tell which way was "up" when the sediments were deposited.

They are used to determine the direction of magnetic north when the sediments were lithified.

Geopetal structures indicate the direction(s) of currents that were present when the sediments were deposited.

These structure are an indication of temperatures when the sediments were lithified into sedimentary rocks.

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Increase in pressure

Addition of water

Through the addition of pyrite by aqueous fluids

Recrystallization removes the impurities.