Answer:
It's caused by burial forces
Explanation:
When sediments are deposited on a basin they begin to accumulate over each others, generating a burial force that produces its compaction. Then, some calcite and silica cements help to join the sediments grains creating rocks. That's what geologists call lithification.
This process allow the formation of sedimentary rocks, which usually are laminated because of the horizontal position of sediments accumulation.
