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
Black River (Chehalis River) Black River (Chehalis River) The Black River is a river in Thurston County in the U.S. state of Washington. It is approximately long with a drainage basin of about . The Black River's source is Black Lake, located about west of Tumwater. The river flows generally south, through the Mima Mounds State Natural Area, then southwest, passing by Rochester and entering Grays Harbor County, then emptying into the Chehalis River in the Chehalis Indian Reservation. The fur trader John Work was the first to describe the Black River in 1824: "The Black River so named from the colour of its