Normal EFR development results in a fairly peaceful group which may have produced a few minor flares. In declining groups, the smaller f polarity spots usually vanish before the dominant spots begin to decay. Most groups finally decay into a single p spot with no plage, which then slowly shrinks and dies out. Deltas are some of the largest and most active areas on the sun. The opposite polarities are generally within two degrees of each other.
Deltas usually form in one of three ways.
Large satellite polarity areas emerge close to existing spots so that the expansion of the emerging flux region pushes a p spot into an f spot or vice versa. It only forms from emerging umbrae, not plage. If the new dipole emerges into plage only, modest flares may occur without delta spot group formation. If it emerges under of collides with an umbra of opposite polarity, the delta spot forms and larger flares occur. If the dipole collides with an umbra of the same polarity, the two do not necessarily merge, but coexist peacefully.