It is a fundamental feature of sedimentary rocks. CROSS-BEDDING is a feature that occurs at various scales, and is observed in conglomerates and sandstones. In geology, the sedimentary structures known as cross-bedding are the (near-) horizontal units that are internally composed of inclined layers. Sedimentary rocks fall into three general categories base on origin and composition:. Cross bedding is very common in beach deposits, sand dunes, and river deposited sediment.
Bedding. Bedding is often the most obvious feature of a sedimentary rock and consists of lines called bedding planes, which mark the boundaries of different layers of sediment. They are used to subdivide successions of sedimentary rock into their beds and are traditionally used to determine the relative order and timing of the accumulation of the sediments forming the beds. Concurrently the character of the bedding planes be they eroded, cemented, bored, bioturbated, or depositional surfaces is used to aid in the interpretation of these sedimentary rocks. The formation of a clastic sediment and sedimentary rocks involves five processes:. Because sediment is deposited in low lying areas that often extend over wide areas, successive depositional events produce layers called bedding or stratification that is usually the most evident feature of sedimentary rocks.
Graded bedding can be used to tell which are the oldest and youngest rocks in a sedimentary sequence because the larger, older grains are at the base of the bed. Sedimentary rock, rock formed at or near the Earth’s surface by the accumulation and lithification of sediment (detrital rock) or by the precipitation from solution at normal surface temperatures (chemical rock). Sedimentary structures include features like bedding, ripple marks, fossil tracks and trails, and mud cracks. They conventionally are subdivided into categories based on mode of genesis.
Crossbedding–reading the rock. Cross-bedding is widespread in three common sedimentary environments: rivers, tide-dominated coastal and marine settings. SUBJECTS Sandstone cross-bedding. Answer: Sedimentary rocks formed at the surface of the Earth, and best record Earth’s environmental, climatic, and biologic history. 1) Bedding: Series of horizontal layers within an outcrop of rock. This produces a sequence of sedimentary rocks that represents the various weathering products of rocks and the distance that these products may be transported from their sources. Sedimentary rocks often have distinctive layering or bedding. Sedimentary rocks are classified into three major groups: clastic, biologic and chemical. Sedimentary rocks are characterized by layers, a feature known as bedding. Bedded rocks often contain fossils and provide a snapshot of periods of earth history. Sedimentary rock often exhibits bedding: that is, the rock has distinct layers in it and is fissile: that is, it splits more easily at the divisions (bedding planes) between the layers.