Dating issues often restrict how far archaeology can demonstrate the contemporaneity of buildings within settlements, especially where relative sequences through stratification cannot be demonstrated. A lack of stratification is generally more an issue in plough-truncated lowland sites; this applies equally to buildings within enclosed settlements (e.g. Boonies; Jobey 1974, RCAHMS 1997) as it does to ‘open’ settlement (e.g. Dalladies; Harding 2004, 99), and restricts reconstruction of settlement form, layout and development. Cropmarks as palimpsests of activity can represent a particular challenge when attempting to reconstruct the distribution of sites and structures at any particular time.
The long-held assumption that houses were occupied for long periods of time as permanent, continuous residences, has been challenged with archaeological evidence from a range of excavated structures (e.g. Halliday 1999; Barber & Crone 2001; Cowley 2003, 2009; Crone 2000; see also theme 9.3). A position is now being approached where the assumption is of shorter, perhaps generational duration for the occupation of a building unless demonstrable otherwise. This too should be a matter of testing, not assumption, with assessment (for instance) of evidence for the degree of repair or replacement in buildings a useful proxy of longevity; it is unwise to rely, for instance, on the existence of ‘floor layers’ (a nebulous concept) or quantities of finds as an indicator of longevity, as it is likely that many houses were kept clean in normal use. It must also be remembered the likelihood of a building going through stages in its life, from freshly made through maintenance to reuse which may bear no relation to its primary purpose (and may generate the bulk of the surviving evidence, if it is turned into a store or dump).
Apparent episodic and seasonal activity has been identified at sites that previously would have been interpreted as permanent and continuous (e.g. Braehead; Ellis 2007). Such evidence is hard to establish in many circumstances but should be in an excavator’s mind, rather than assuming permanence.
At some excavated Atlantic settlements (e.g. Dun Mor Vaul, MacKie 1974, 1997; Howe, Ballin Smith 1994; Beirgh, Harding and Gilmour 2000) the evidence does suggest occupation for several centuries, apparently continuously. These issues are fundamental to how the broader distributions of settlement remains are interpreted as representative of stable and sedentary or shifting and mobile communities.
In the cases of both short- and long-term occupation, there is the possibility to test this in good circumstances, through careful excavation and fine-grained dating of the sequence; where circumstances present themselves, this should be seized.