Kent coastline of Kent is continuously changing, due to tectonic uplift and coastal erosion. Until about 960, the Isle of Thanet was an island, separated by the Wantsum channel, formed around a deposit of chalk; over time, the channels silted up with alluvium. Similarly Romney Marsh and Dungeness have been formed by accumulation of alluvium. Kent's principal river, the River Medway, rises near East Grinstead in Sussex and flows eastwards to Maidstone. Here it turns north and breaks through the North Downs at Rochester, then joins the estuary of the River Thames as its final tributary near Sheerness. The Medway is
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