Grain Size Chart
The Size Chart is a must have for field geologists to describesamples. This pocket size chart is not only handy and cheap it’s also cost effective for the professional in the field.
The chart has recessed die-cut sample cavities filled with precisionsievedsedimentary particles. The particles are permanently mounted to the chart so they will not wear out. The samples are classified according to the Wentworth scale so geologists can classify and describe grain sizes in an organized and standardized way. The chart includes categories such as very coarse sand, which is essential for initial site evaluations and soil descriptions. Grain classification and analysis of sedimentary rocks is key to understanding the processes of erosion, transport and deposition that formed them.
With the Grain Chart geologists can quickly and easily refer to the grain classification for their samples. The compact size of the chartfits in a pocket, backpack or field bag so it’s always with you when you need it. Its portability makes it perfect for fieldwork and on site analysis so you don’t need bulky reference materials or equipment.
The precision sieved sedimentary particles on the chart were selected to represent a range of grain sizes commonly found in geologic samples. So geologists can classify and describe grain sizes with precision.
The Size Chart is a proven and trusted tool used by field geologists worldwide. Its simple and rugged design makes it a long lasting investment that can withstand the demands of field work. Whether in the lab or in the field this grain chart is an essential tool for geologists.
Don’t settle for anything less than accurate size classifications. Choose the Grain Chart and be consistent and reliable every time.
Grain size is a fundamental concept in sedimentary geology, meaning the average diameter of clasts (particles) of clastic sediments and rocks. Grain size is key to classifying sediments and rocks, understanding their origin and depositional environment and predicting their physical properties. In this article we will explore the world of grain size, classification, measurement and applications.
Grain Size Classification
Size classification is a critical step in sedimentary geology where we can categorize sediments and rocks into different classes based on their grain size. The classification system helps in distinguishing between different types of particles, such as sand grains, silt, and clay, which is crucial for understanding sedimentary processes. The most widely used classification system is the Udden-Wentworth scale which divides sediments into four actual grain samples and major classes: ruditic (> 2 mm), arenitic (0.0625 – 2 mm), siltitic (0.004 – 0.0625 mm) and lutitic (< 0.004 mm). These classes are further sub divided into more specific categories like coarse sand, medium sand and fine sand. The Wentworth scale provides a framework to understand the processes that formed sediments and rocks, the agent of erosion/transport and the velocity of the current that transported the sediment.
Grain Size Measurement and Applications
Sieve Analysis and Other Measurement Methods
Grain size can be measured by several methods including sieve analysis, contouring/counting on thin sections and visual comparison with grain charts. Sieve analysis is the most common method where a sediment sample is passed through a series of sieves with decreasing mesh sizes to separate particles of different sizes. The resulting grain size distribution can be plotted as a size frequency distribution to get information about the texture and composition of the sediment. Phi units (Φ) are also used to describe sediment size in hydrogeology, with the conversion to real world units given by the formula: Diameter (mm) = 1/2^n where n = phi (Φ) value.
Practical Uses of Grain Size
Grain size has many practical uses in sedimentary geology:
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Understanding the origin and depositional environment of sediments and rocks
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Predicting the physical properties of sediments and rocks, strength, density and porosity
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Classifying sediments and rocks into different classes for classification purposes
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Interpreting the geological history of an area, tectonic and climatic conditions
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Accurately identify grain size and potential economic deposits, oil and gas reservoirs and mineral deposits
In summary grain size is a fundamental concept in sedimentary geology and its classification, measurement and applications are key to understanding the origin, composition and properties of sediments and rocks. By using grain charts, sieve analysis and phi units geologists can get valuable information about the geological history of an area and make informed decisions about resource exploration and management.