The architecture on graves like these – a little fenced enclosure – is called a crib. Despite the association that you might initially have, a crib grave is not necessarily for an infant or child. It probably is meant to convey a sense of comfort and security on those who come to visit a deceased love one, though. Our cribs that we slept in as infants were places where we were warm and safe, carefully watched over by guardians.
As I said before, despite its strong harkening to infancy, the crib grave design is used for adults as well as children. Most cribs I have seen date to the 19th century.
A Grave Concern 