Sedimentary rocks are the result of lithification of sediments, the loose material that accumulates at the surface as the result of weathering and transport and deposition of the weathered materials. Lithification is a rock forming process that involves:

• Consolidation - This is mostly due to pressure. The weight of overlying sediments results in compaction, a reduction in pore space and removal of water
• Cementation - The deposition from solution of a soluble substance. This fills any spaces between grains (pore space) and cements or glues the grains together. There are three common types of cement:
• Calcite, probably the most common because calcium is easily dissolved in groundwater.
• Silica. This is less soluble than calcite. It forms much stronger and harder cement.
• Iron oxide (Fe₂O₃). This is the red mineral hematite and is the reason for the red color of some rocks.

A superb natural laboratory for the study of sedimentary rocks is the Grand Canyon.