From Warrington the Mersey, still keeping a sinuous course, begins to expand, and when next it comes into touch with the ship-canal, which it does at a point known as Randall's Creek, it assumes estuarial form, and markedly so just before reaching Runcorn. Then there is a sudden change, caused by the outswelling of both banks of the river, the result being that the Mersey is contracted to about 1,200 feet across, after being more than twice that width. This contraction, known as Runcorn Gap, lies between Widnes Point on the Lancashire side, and Runcorn on the Cheshire side. At this, the nearest point to the upper estuary proper, the Mersey is crossed by a high level bridge, giving the London and North Western Railway access to Liverpool. Runcorn has been made by canals; three, approaching from different directions, touch the Mersey there. The ship-canal lies to the north of the town, after passing through a cutting extending to a depth of 66 feet, the deepest on the route. Lying under the railway bridge, and coming close to the river, it soon finds itself wholly in the bed of the Mersey, separated from the stream by a massive concrete wall, for which in one place a foundation had to be made 70 feet down. There were considerable docks and warehouses here before the greatest of the canals gave additional claim to Runcorn to be considered a seaport. Ethelfreda, daughter of Alfred the Great, is said to have founded the town; and antiquaries are pleased to regard the name as a corruption of Runcofan, from the Anglo-Saxon "cofa," a cove or inlet. The locks on the canal here are so constructed as to enable vessels to leave or enter at any state of the tide. Widnes, on the opposite side of the river, is a busy, thriving manufacturing town, with chemicals as its leading commercial product, but doing a good deal also in various branches of the iron trade.