A clearance cairn is an irregular and unstructured collection of fieldstones which have been removed from arable land or pasture to allow for more effective agriculture and collected into a usually low mound or cairn. Commonly of Bronze Age origins, these cairns may be part of a cairnfield (a collection of closely spaced cairns) where some cairns might be funerary.[1] Clearance cairns are a worldwide phenomenon wherever organised agriculture has been practised.[2][page needed]