Metalling
The term road metal refers to the broken stone or cinders used in the construction or repair of roads or railways, and is derived from the Latin metallum, which means both "mine" and "quarry". Metalling is known to have been used extensively in the construction of roads by soldiers of the Roman Empire (see Roman road) but a limestone-surfaced road, thought to date back to the Bronze Age, has been found in Britain. Metalling has had two distinct usages in road surfacing. The term originally referred to the process of creating a gravel roadway. The route of the roadway would first be dug down several feet and, depending on local conditions, French drains may or may not have been added. Next, large stones were placed and compacted, followed by successive layers of smaller stones, until the road surface was composed of small stones compacted into a hard, durable surface. "Road metal" later became the name of stone chippings mixed with tar to form the road surfacing material tarmac. A road of such material is called a "metalled road" in Britain, a "paved road" in Canada and the USA, or a "sealed road" in Australia and New Zealand.
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