ABSTRACT
It is an unfortunate general fact in archaeological fieldwork that surveys are taken only of features which are identified in the field: that decisions are taken on the basis of what is already known, not what might be discovered from a survey. So medieval earthworks are booked with readings taken from the ‘significant’ points (which are subjectively chosen) of each identifiable feature. Banks may be represented by the highest points taken along their length, and by their footing with the surrounding terrain. The data obtained from such work is usually quite adequate for the sort of plan intended for publication, but seldom tells the fieldworker anything more than he or she knew before planning. The possibility is overlooked that there may be features present which are invisible to the fieldworker.
