There are several types of coastal protection measures that can be used to reduce erosion. Hard engineering options like groynes, gabion cages, revetments, seawalls, and rip rap absorb wave energy through rigid structures. Groynes interrupt water flow perpendicular to the coast to limit sediment loss. Gabion cages are stacked rock-filled wire cages that act as temporary barriers. Revetments are sloped stone or wood structures that absorb wave energy. Seawalls are massive vertical walls that deflect waves. Rip rap is rock or concrete rubble that minimizes erosion. Beach replenishment involves adding new sediment and is considered soft engineering since it has a more natural appearance and fits better within the environment.