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It has three meanings in soil science:
1.a size fraction of the soil
2.a texture class name
3.a class of minerals
1.a size fraction of the soil
2.a texture class name
3.a class of minerals
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As a size fraction of the soil, clay has a diameter of?
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Soil Types/Property
Enviro. Techniques Test #1 - Part C
| Question | Answer |
|---|---|
| It has three meanings in soil science: 1.a size fraction of the soil 2.a texture class name 3.a class of minerals | Clay |
| As a size fraction of the soil, clay has a diameter of? | less than 0.002 mm in diameter. |
| Clay particles less than .001 mm are called... | colloidal particles |
| T/F: not all clay is strictly colloidal, but even the larger clay particles have colloidal-like properties. | True |
| T/F: The least active portions of the soil are those in colloidal state. | False - The most active portions of the soil are those in colloidal state. |
| What has these three distinguishing properties of: A)Great effective surface area (B)Capacity to fix and hold solids, gases, salts, and ions (C) The tendency to hasten and or retard chemical reactions (catalysts) | Colloidal clays |
| Low permeability, high dry strength, low resistivity and plant interactions of slow intake of water, rich in nutrients are... | Unique clay properties |
| T/F: Nearly all clay in natural soils is colloidal, and almost all colloidal clay is crystalline. | True |
| T/F: The mineral colloids are the most important fraction of the soil because of their physical and chemical activity. | True |
| Two basic groups of clay minerals are... | Silicates and non-silicates. |
| Which group of clay is composed of silica, aluminum and oxygen? | Silicate clays |
| Which group of clay is composed of hydrous oxides of iron and aluminum | Non-silicate clays |
| Formed in temperate regions and dominate agricultural areas of the world? | Silicate clays |
| Dominant in highly weathered soils in tropical regions? | Non-silicate clays |
| Vermiculite, kaolinite (non-swelling for dishes) and montmorillonite (bentonite) are... | Silicate clays |
| Has well formed crystals... | Silicate clays |
| Has varied forms of crystals... | Non-silicate clays |
| The crystals of these clay minerals are plate-like in nature, being built up of flat crystal units. | Silicate clays |
| All of these clay crystals are composed of one or two types, known as two-layer and three-layer crystals. | Silicate clays |
| Consists of one layer of silicate and the other layer of aluminum, all in definite spatial arrangement (i.e. kaolinite). | The two-layer type of silicate clay. |
| Crystals have two outside layers made of silica in the middle layer of aluminum (i.e. illite and montmorillonite). | Three-layer type of silicate clay. |
| Plasticity, cohesion, shrinkage and swelling are very low. Used in bricks and China (pottery). | Kaolinite clay |
| Plasticity, cohesion, shrinkage, and swelling are greater than in kaolinite. Properties are between kaolinite and montmorillonite. | Illite clay |
| A type of clay whose composition and structure allows for greater shrinkage and swelling. | Montmorillonite clay |
| More surfaces are exposed as clays expand and more absorptive capacity of water between Crystal sheets. | Montmorillonite clay |
| Is the dominant clay mineral in bentonite (altered volcanic ash) which is used for sealing wells. | Montmorillonite clay |
| T/F: A single clay crystal is called “micelle” | True |
| T/F: Each clay crystal is an negative electric charges called an ion. | True |
| T/F: Not all clays absorb water on their surfaces or lose water from their surface as the soil water content changes. | False - all clays absorb water on their surfaces or lose water from their surface as the soil water content changes. |
| T/F: Some clays allow water into the interlayer spaces between layers of the crystal. | True |
| Feldspar (orthoclase and plagioclase), Amphiboles (hornblende), Pyroxene and Micas (biotite and Muscovite) weather to form? | Clay |
| Are the openings between the grains making up a soil. | Pores |
| Describes the amount of openings between the grains making up a soil. | Porosity |
| T/F:Pore spaces do not occur in rocks as well. | False - they do. |
| T/F:Pores can either be connected or not connected. | True |
| Has deposits that are considered poorly graded and have high porosity. | Well sorted deposits |
| What can be calculated by dividing the pore volume by the total volume, and it is expressed as percent. | Pore spaces |
| Has deposits that are considered well graded and have lower porosity. | Poorly sorted deposits |
| What soil class has fairly large, well-connected pores? | Gravels and Sands |
| What soil class has smaller pore spaces than gravel and sand? | Silt |
| What soil class has a large amount of pore spaces but each space is small and pores are not well-connected, and the pathway is tortuous. | Clay |
| Represents the ideal volume of pore water for plants. | Field Capacity |
| T/F: Above field capacity, water is not influenced by gravity and drains below the root zone quickly. | False - Above field capacity, water is influenced by gravity and drains below the root zone quickly. |
| Represents the moisture content below which plants are no longer able to uptake water from the soil. | Permanent Wilting Point |
| Represents the water present in the soil below permanent wilting point. | Hygroscopic Water |
| The remaining water adheres to soil particles and is unavailable to plants. | Hygroscopic Water |
| T/F: Porosity provides pathways for oxygen, organisms and water (carries nutrients and provides moisture). | True |
| T/F: Porosity is also a potential pathway for contaminants. | True |
| Is the ability of a porous material to allow fluid to flow through it and is commonly symbolized with a letter K. | Permeability |
| It is also known as hydraulic conductivity | Permeability |
| T/F: Any material with voids is porous, and if the pores are interconnected it possesses permeability. | True |
| T/F: The permeability of soils and bed rock is not a concern in the drainage of soils, the drilling of water wells, migration of landfill leaching its and other contaminants. | False - it is a concern. |
| Which soil characteristic of an unknown soil can be determined by using a device called a permeameter, and the variables expressed in Darcy’s law. | Permeability |
| Expresses the relationship between the soil’s solid phase and pore phase. Used in engineering soil mechanics, and expressed as a decimal. | Void Ratio |
| Defines the flow of water through soil. | Darcy’s Law |
| Typically, soils are a mixture of gravel, sand, and fines (silt and clay) whose relative proportions determine the... | Soil Texture |
| What contains areas that represent the allowable combination of the three sizes and separates for each textural class name. | The soil textural triangle |
| T/F: The texture of the soil will determine how the soil behaves under certain conditions. | True |
| Two methods for describing a soil sample’s particle size distribution are: | the field identification tests and the particle size analysis. |
| Which test to determine soil particle size uses sieves to separate the particles. | The particle size analysis |
| Soils may be grouped into three major divisions: | Coarse-grained, fine-grained, and organic. |
| Soils may be described briefly as those made up largely of particles visible to the naked eye. | Coarse-grained Soils |
| These coarse-grained soil particle sizes include: | Boulders, cobbles, gravel, and sand. |
| Are made up of particles not visible to the naked eye. | Fine-grained soils |
| Fine-grained soils may be classed as: | Silt, clay or a combination of both. |
| T/F: The ratio of combined silt and clay is categorized on the basis of their behavior as determined in simple indicator tests. | True |
| T/F: Plasticity and particle size can be judged accurately without the use of refined testing techniques. | False - they cannot be judged accurately without the use of refined testing techniques. |
| This group is placed in a separate group because of their appreciable content of organic matter. | Organic soils |
| A mixture of some organic material with predominantly mineral soils is called? | Partly organic soils |
| In "Basic Field Soil Tests" what are the four descriptors for coarse-grained and fine-grained soils? | Colour, odor, moisture, density, and structure. |
| This descriptor indicates depth of weathering in the soil and may also be helpful in identifying similar soils in the same region. This descriptor can also indicate soil drainage and water table fluctuations. | Colour |
| A distinct lack of color in soil contributing to an overall grade or brownish color. | Gleying |
| Gleying usually occurs where soils are_________for much of the year. | Saturated |
| Is a condition caused by movement of groundwater through the soil and the resulting redistribution of iron within the soil. | Mottling |
| Such saturated soil conditions can lead to anaerobic conditions, and the movement of iron produces______ __ ____ ___ _____ soil colors interspersed with the dominant color. | blotches of gray and reddish-brown |
| This descriptor will normally indicate the presence of organic matter or contaminants. | Odour |
| Particle shape is a descriptor used for coarse-grained or non-cohesive soils. The terms used to describe grain shape are: | Angular, sub angular, rounded and sub rounded. |
| __________ is the term applied to the particle size distribution of the soils. | Grading |
| A descriptor for fine-grained soils (including cohesive clays). ___________ varies mainly with water content and density, and is described by the adjectives hard, stiff, firm and soft. | Consistency |
| _______ is the ability to change shape and retain me impressed shape when the stress is removed. | Plasticity |
| The degree of plasticity of soils is the range in _______ ______through which the soil remains plastic horse capable of being molded. | moisture content |
| _____ _____ of the soil is defined as the moisture content at which a thread of soil 1/8 inch in diameter will begin to crumble when rolled further. | Plastic Limit |
| Also known as the shaking test. | Dilatency Test. When a wet sample of soil is shaken vigorously in the hand, the surface will become glossy and show free water. When the soil sample is pressed, the moisture on the surface is reabsorbed (dilates) into the sample. |
| When a moist lump of soil is stroked with considerable pressure with the flat of a pen knife blade, or spatula, the type of surface created indicates the type of soil. What test is this? | Shine test |
| Results of the shine test indicate the samples' composition. ______ is indicated by a dull surface, and _____ is indicated by a shiny surface. | Silt, clay. |
| The breaking strength is an indication of the relative amount of silt or clay. Which test determines this? | Dry Strength Test |
| Low dry strength is indicated when the soil powders or is crushed easily in the fingers and may indicate which type of soil? | Sandy silt or silt. |
| Medium dry strength is shown by difficulty in powdering or crushing the soils by finger pressure, but the soil can be broken into pieces without great difficulty. This state indicates which type of soil(s)? | Silty clays and clayey silts of medium plasticity. |
| High dry strength is indicated when the Pat of dry soil cannot be broken with the fingers and this indicates the sample is made up mostly of? | Clay! |
| After the Dilatency test, try to roll the soil sample into an eighth of an inch thread. Which test is this? | Plasticity Test |
| If you cannot roll a thread, then the sample is? | Mostly silt. |
| If you can roll a thread easily, then the sample is mostly? | Clay |
| If you can roll a thread but it breaks soon after your sample is? | A a mixture of clay and silt. |
| Whether or not the sample sticks to your hands, which test is this? | Stickiness test. |
| ____ sticks to the fingers when wet, and does not wash off readily, whereas _____ will wash away easily or brush off easily, when dry. | Clay, silt |
| this test involves placing a small amount of dry soil between your top and bottom front teeth rubbed her teeth back and forth and note the grittiness of the soil between your teeth. | Grit (toothpaste) Test |
| A gritty feel indicates the presence of _____, or even possibly very fine sand. If there is no gritty feel, it indicates the soil consists of _____. | Silt, clay |
| Particle sizes - greater than 200 mm | Boulders |
| Particle sizes - 75 mm to 200 mm | Cobbles |
| Particle sizes - 5 mm and 75 mm | Gravel |
| Particle sizes - 0.05 mm and 5 mm | Sand |
| Particle sizes - less than 0.05 mm | fine-grained soils i.e. silts and clays |
| Particle sizes - 0.05 mm to .002mm | Silt |
| Naming Soil Samples - “and” denotes approximately? | 50%-50% split Ex:If it’s determined that the sample is 50% sand and 50% gravel, then identify or name the soil as “sand and gravel”. |
| Naming Soil Samples - “y” denotes approximately a? | 60%-40% split Ex:If it is determined that the sample is 40% sand and 60% gravel, then identify or name your sample as “Sandy gravel”. |
| Naming Soil Samples - “some” denotes approximately? | 70%-30% split Ex:If it is determined that the sample is 70% sand and 30% gravel, then identify or name the soil sample as “sand with some gravel”. |
| Naming Soil Samples - “trace” denotes approximately? | less than 10% Ex:If it is determined that sample is 90% sand and less than 10% gravel, then identify or name your sample as “sand with a trace of gravel” |
| ____ ______ is the term applied to the nature of soil mass in place. | Soil Structure |
| ____ ______ is the arrangement of soil particles into secondary units called aggregates or peds. | Soil Structure |
| Soil structure is most usefully described in terms of: | Grade (degree of aggregation, i.e. how easy will it crumble under pressure). Class (average size), and Type of Aggregates (form or shape). |
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ctherria
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