During compaction, strain is localized at grain contacts. Pressure increases solubility. If pore water is present, this results in localized dissolution at the grain contact. This results in irregular, sutured contacts between the grains. Stylolites in more cemented rocks, pressure solution takes place along much more extensive surfaces - these are stylolites .
Dissolution often starts along a bedding surface, due to overburden pressure.
A burial depth of at least several tens of metres is required for stylolite formation. Stylolites cross the whole rock, cutting grains, matrix and cement. They often have a zigzag form, due to differences in solubility of the different components, e.g. skeletal fragments may be less soluble than micrite matrix. The less soluble parts form 3-dimensional 'fingers', extending into the more soluble parts. The amplitude shows the minimum thickness of dissolved material.