Geography of Kent and Dungeness have been formed by accumulation of alluvium. Kent's principal river, the River Medway, rises near Edenbridge and flows some 25 miles (40 km) eastwards to a point near Maidstone, when it turns north. Here it breaks through the North Downs at Rochester before joining the River Thames as its final tributary near Sheerness. The river is tidal as far as Allington lock, but in earlier times cargo-carrying vessels reached as far upstream as Tonbridge. The Medway has captured the head waters of other rivers such as the River Darent. There are other rivers in Kent, most notably the
Borough of Maidstone for cargo-carrying craft as far upstream as Tonbridge, and it was only in the 19th century that the railways brought any change. More recently, various works have been carried out to control the frequent flooding in the clay vale upstream of Maidstone. Maidstone, as its importance warranted, has been the hub of roads for many centuries. It lies very close to the Pilgrims' Way; and two Roman roads met south of the town: one from Rochester to Hastings the other branching off to the East Kent coast and Dover. In the 18th century came the turnpiked roads. One of the