Most bowl barrows survive in the form of earthworks, below ground structures, or cropmarks. Soil and geology greatly influence the survival and potential of bowl barrows in two main ways: firstly through the nature of the materials used for their construction, and secondly through the kinds of later prehistoric and post-prehistoric land-use that will have taken place over and around a site. Thus on soft bedrocks (eg. sand, gravel etc.) which have been heavily exploited in post-prehistoric times the survival of bowl barrows is very poor in comparison to areas of hard rocks (eg. limestone, sandstone, chalk, granite) which have been subject to relatively low intensity land-use. Variations caused by these factors can be seen at the local as well as the national level, and the survival of bowl barrows can vary greatly even within a single county.
Excavations clearly demonstrate that the structure and use of a bowl barrow can only be properly understood if some or all of the mound remains. Archaeologically, the mound is the most important component of a bowl because it stratigraphically links all the other components to one another and may indeed contain some important components (eg. primary, satellite, and intrusive burials). The mound and its contents are also the most vulnerable to erosion because they stand above ground level.
The bedrock-cut features such as deep graves and any surrounding ditches are the least vulnerable features as only wholesale disturbance of the natural bedrock will destroy them. It must, however, be noted that some types of bowl barrow have no components that penetrate the subsoil at all; many of these types may have already been lost without trace. Many of the ring-ditches that are thought to have been barrows but which upon excavation appear to be "empty" undoubtedly represent the last vestiges of types of bowl barrow in which the only rock-cut component is the quarry ditch.
The mounds of most bowl barrows preserve abundant evidence about the construction and phasing of the site; in many cases whole episodes or phases of use are represented only by components in the upper layers of the mound. Typically the materials used to build the mound will contain evidence about the environment at the time of construction, and in the case of turf mounds it is sometimes still possible to identify and study individual sods. Where the source of materials used in constructing the mound includes domestic debris or material relating to other activities this too will be preserved.
Beneath the mound will be traces of the old (pre-barrow) land surface which will usually contain evidence of previous land-use, for example, settlement, agriculture, ritual etc. Heavy denudation of the mound often causes the edges of the old land surface beneath it to disintegrate and accordingly it must not be assumed that the entire area of the mound will preserve an old ground level. It has also been noticed that ground surfaces below substantial barrows are higher than the modern ground level around about because outside the zone of protection represented by the mound chemical and mechanical has significantly lowered the surface of the land.
The total range of material available at any given site will depend largely upon the soil prevailing chemistry. The compaction of the mound is also important; boulder cairns with abundant voids preserve less in the way of macroscopic and microscopic remains than dense mounds of turf and soil. Very few mounds contain anaerobic deposits because of their situation; exceptions include those in low-lying positions covered in alluvium or peat, and those in upland areas covered by blanket bog.
The ditches will contain deposits relating to the environment around the site when in use and during its decay, the dating of the site, and perhaps evidence of rebuilding and refurbishment. Some ditch deposits may be waterlogged, although few will have remained wet since prehistoric times. It cannot be assumed that the most clearly defined ring ditches on aerial photographs are also the most well preserved; often the converse is true.
The burial deposits are in many senses the most spectacular evidence from bowl barrows, contributing not only information on patterns of ritual, burial rites, physical anthropology, diet, pathology, and disease, but also providing an assortment of finds, some of very high quality, and information on patterns of association and deposition. Data from funerary contexts is of prime importance in studies of artefact types. In exceptional circumstances, such as waterlogging, mineralization or carbonization, the remains of wooden structures containing burial deposits will survive.
No historical records are available for bowl barrows, but place-name evidence, folklore, and antiquarian references to investigations and explorations can increase understanding of the site. Early land charters can be important for authenticating the antiquity of a mound (although not necessarilly its classification as a bowl barrow).