The posterior of these keels shows weak crenulation. Several foliations may be present in a rock, giving rise to a crenulation. Eventually, the crenulation foliation overprints the S1 foliation. Crenulation cleavage contains microlithons that were warped by a previous foliation. "Crenulation cleavage" and "oblique foliation" are particular types of foliation. Crenulation may also be the incipient foliation plane which precipitates shearing.