CROSS-BEDDING is a feature that occurs at various scales, and is observed in conglomerates and sandstones. See: trough cross stratification and other examples at: dune cross stratification See ripple cross lamination on Mars: martian ripples. Watch the USGS bedform movies described at: USGS Bedforms page Bedforms and Flow Velocity- The size and shape of subaqueous bedforms depends on flow strength and grain size and can be used to interpret ancient flow characteristics in a depositional environment from looking at sedimentary rocks. Cross beds form from running water. Cross beds can therefore form in any environment with moving water, such as braided or meandering rivers, shorelines of lakes or oceans, or in submarine settings which are affected by deep sea currents. Back to depositional environments.
Trough cross-stratification is generated by the migration of linguoid ripples or dunes. Bedforms: features in sedimentary rocks formed by the interaction between flow and the sediment composing the bed. Sinuous and lenticular dunes produce trough cross beds. Ripple marks are one of the commonest features of sedimentary rocks, both in recent and ancient sediments. Note the trough cross-bedding on the cut that is perpendicular to flow (i.e. the v-w cut) This figure shows flow along the bed across a set of sinuous-crested bedforms.
Includes plane bedding and cross-bedding. In what depositional environment would one most likely expect to find plane bed laminations? The point of flow reattachment is where most erosion occurs often forming troughs with long axes parallel to current flow. Within the major beds, cross-bedding is common. Almost all sedimentary environments produce characteristic types of cross-beds; as one example, the lee faces of sand dunes (side not facing the. The demarcation line between paralic/deltaic and marine depositional setting as illustrated in the Figure below. Upper foreshore planar-cross bedded sandstone of wave swash zone overlying trough-cross stratified sandstone zone of breaking waves. Current ripple beds wave ripple beds, hummocky cross-beds contorted beds.
Sedimentary Structures Facts, Information, Pictures
Trough Cross Bedding Tabular Cross Bedding Apparent Flow Direction Apparent Flow Direction True from GEOL 2401 at Texas Tech. Different depositional environments exhibit these variations and can thusly be connected to specific sedimentary structures.