Pict. 2.3. Cross-laminated sand at Radostyán

Sedimentary structures have many types in the geological material. Unstratified beds, planar stratification, cross stratification and gradation are the most important among these.

It can be occur that sediment units doesn’t stratified. It can be formed because of primary and secondary causes also. Originally unbedded sediments are the glacial sediments (tillite) or the reef sediments (Pict. 2.4.). Secondary unbedding can be formed because of the bioturbation of inbenthos organisms (Pict. 2.5.).