<P> The burial vault or burial liner is designed to prevent the weight of earth or heavy cemetery maintenance equipment from collapsing the coffin beneath . Coffin collapse will cause the ground to sink and settle, marring the appearance of the cemetery and making it harder to maintain . Burial vaults originally emerged as a means of ensuring that grave robbers could not easily access a coffin and remove valuables, clothing, or even bodies from the coffin . Early vaults were made of wood (the "rough box"), although by the middle of the 1800s brick, iron and later steel vaults were used . By the late 1800s, the fashion of burying the deceased with jewelry lost favor . However, the value of burial vaults in ensuring that the ground did not settle over graves was seen, and burial vaults began to be more widely used . By the early part of the 20th century, concrete (and, later, reinforced concrete) vaults became more common . </P> <P> Although quite commonly used in many industrialized countries, the burial vault is very much a funerary item used almost exclusively in the 20th century . In the United States, the burial vault was largely unknown until the 1880s when the L.G. Haase Manufacturing Co., which owned a cemetery in Illinois, conceived the burial vault as a means of adding a product line to their funerary sales . As late as 1915, only 5 to 10 percent of funerals in the United States used a burial vault or liner . In the 1930s, company owner Wilbert Haase, who had an interest in Egyptian mummification, began promoting the sealed (or "waterproof") vault as a means of allegedly protecting the body from water, microbes, and vermin . The Haase company later purchased several plastics companies, and began manufacturing plastic burial vaults as well . The company dominates the American burial vault market today, with about 12 percent of all vault and liner sales . </P> <P> A burial vault encloses a casket on all four sides, the top, and the bottom . Modern burial vaults are lowered into the grave, and the casket lowered into the vault . A lid is then lowered to cover the casket and seal the vault . Modern burial vaults may be made of concrete, metal, or plastic . Because the sides of the burial vault are attached to the bottom of the vault, the burial vault is generally stronger than a burial liner . Some burial vaults reverse the construction, so that only a base is placed beneath the coffin . The lid consists of the four sides and the top . These types of burial vaults allow a better seal between the lid and base . </P> <P> A burial liner is similar to a burial vault, but does not have a bottom . With a burial liner, the coffin is lowered directly onto the earth . The burial liner is then lowered over the casket . Modern burial liners may also be made of concrete, metal, or plastic . Many come in a wide array of colors, even stripes . </P>

How far does a coffin go into the ground