The straighter the hedge and more square the field corners generally speaking the more recent they are likely to be. Even by looking at the pattern of fields on a modern map, hedges can be identified with Bronze Age smallholdings, mediæval burgage plots, deer parks, mining, transport and other purposes.
Hedges give evidence of their status as historical monuments in their siting, shape and size, and pattern of stone cladding. Their structure sits on previous land use, sealing it in the ground and preventing casual interference over the millennia. Hedges contain material which may have archæological importance, and they support vegetation that reveals the earlier nature of the land, or the site of long-vanished human habitation or activity. Some have stone artefacts such as querns, cupstones, granite troughs or early Christian crosses built into their structure.
Cornish hedges are sometimes called Celtic hedges because similar hedges appear along the Atlantic seaboard as far north as the Orkneys and to the south in the Channel Islands and Brittany. Some of these may be seen as degenerate Cornish hedges, being lower and less structured, and mixed with the ordinary English type of hedgerow. Cornwall, at the centre of the Atlantic arc, with its fine examples has the greatest concentration of locally diverse types of these hedges still surviving in Britain. They are a rare instance of major prehistoric remains still in everyday use for their original purpose.