What is know as Stratra?

 

The strata are also known as layers. The sedimentary rocks are called stratified rocks because they are formed by the deposition of various layers/ strata one above the others with the time.  

Examples of sedimentary rocks

Sand stone − Formed by deposition of sand

Limestone − Formed by deposition of calcium carbonate

Shale − Formed by deposition of fine clay

Conglomerate (pudding stone) − Formed by cementation of small rounded pebbles