What Are the Kinds of Sediments in a Rock Cycle?

Clay and Silt

• In geology, clay is a particle of rock smaller than 1/256 millimeters in diameter and silt is between 1/256 and 1.16 millimeters. When clay (and sometimes silt) particles in riverbeds and swamps are compressed together over millions of years and harden, they form shale, the most abundant of sedimentary rocks. Shale comes in a variety of colors, is known for its ability to break into thin pieces and is highly valued for its natural gas and oil content and for its use in making crafting clay. When exposed to extremes of heat and pressure over time, shale metamorphoses into slate.

Sand

• Sand is geologically defined as a rock particle between 1/16 and 2 millimeters in diameter. Sand is usually quartz. Sand accumulates in beaches, deserts, flood plains and deltas and over time gets cemented and compressed by the elements to become sandstone. Different colors in sandstone represent different types of minerals in the sandstone and different years of formation. Sandstone metamorphoses into quartzite.

Conglomerate

• Conglomerate is a sedimentary rock made of particles larger than sand, with spaces between the rocks, filled by a natural cement called a matrix. It's usually formed when fine sand or clay fills spaces between pebbles or boulders on fast-flowing riverbeds or beaches with strong waves and hardens over time. Metamorphosed conglomerate usually contains the original colors and textures of the parent rock; however, since the metamorphic process has recrystallized the matrix, it is called metaconglomerate. When large pieces of rock have been affected by the process it is called stretched pebble conglomerate.

Non-clastic

• Non-clastic sediments come in two kinds: chemical and organic. Chemical rocks form when dissolved materials precipitate from a solution like rock salt, which forms when ocean water evaporates leaving salt behind, or flint, which forms in a complex process involving silicone dioxide, silica and ground water. Organic rocks, like coal and limestone, form from fossils. Limestone forms in shallow, warm, calm waters as shells, skeletons and other organic debris get compressed together, and coal forms from accumulation of dead plant debris in muddy swamp environments.