After the two rivers merge, the Avon then turns south east away from the Cotswolds and then quickly south into the clay Dauntsey Vale, where it is joined by the River Marden, until it reaches the biggest town so far, Chippenham. The wide vale is now known as the Avon Vale, and the river flows on via Lacock to Melksham, then turns north-west through Bradford on Avon, where the centre of the town grew up around the ford across the river Avon, hence the origin of the town's name ("Broad-Ford").[7] This was supplemented in Norman times by the stone bridge that still stands today. The Norman side is upstream, and has pointed arches; the newer side has curved arches.