These rock fragments can vary greatly in size, from microscopic clay particles to very large boulders. Clastic Sedimentary RocksĬlastic sedimentary rocks are made up of little pieces of pre-existing rocks, compacted and cemented together to form a new rock. For ease of reference and identification, I have kept things fairly general while still covering all the sedimentary rock types. For a lot of the rock types, there are also several sub-varieties that could easily use their own descriptions. I have listed and described many varieties of sedimentary rocks below, but not everyone agrees on certain definitions or classifications. These groups are based on how the sedimentary rock is formed and, in general, all of the rocks within each group will tend to have similar characteristics. There are so many types of sedimentary rocks that it can be hard to keep track of them all, but thankfully things are made a little easier by dividing them into three general groups. Pictures & Descriptions of Sedimentary Rock Types I’ll walk you through how to determine what type of sedimentary rock you have and then provide some helpful tables to ID your rock. This procedure might seem a little daunting at first, but it is actually quite simple. If it is organic or chemical, determine the rock’s composition and look for unique characteristics to arrive at an identification. If it is clastic, examine the sizes and shapes of the fragments to determine the rock type. To identify a sedimentary rock, first determine if it is clastic, organic, or chemical. By going through this procedure you can almost always confidently arrive at a solid classification for your sedimentary rock. Sometimes it can be very difficult to identify your sedimentary rock even with pictures and descriptions to compare it to, which is why it is usually best to take a methodical, step-by-step approach to the identification process. I’ll go into how to further classify and identify sedimentary rocks, with pictures and descriptions of specific types. Sedimentary rocks come in so many distinct varieties that sometimes it can be hard to see how one is even remotely related to the other. Sedimentary rocks may be almost any color depending on the source of the sediment.Ĭlassifying rocks as ‘sedimentary’ is only the beginning. Grain sizes can range from microscopic clays to large boulders. In general, sedimentary rocks display grains that are cemented together, often with visible layers, fossils, or unique features like mud cracks or ripple marks. If you’re trying to identify a sedimentary rock it helps to know what they typically look like. Sedimentary rocks are typically classified based first on the process of sediment deposition and then by grain size and composition. There are many different types of sedimentary rocks, and if you know what to look for it can be fairly easy to identify them and distinguish them from other rock types. When most people think of sedimentary rocks images of colorful sandstone layers in picturesque canyons come to mind, but there is a lot more to them than that. Sedimentary rocks are some of the most interesting and widespread rocks found in nature.
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