94 GEOLOGY OF THE ISLE OF WIGHT 



with those of the Isle of Wight. We must imagine 

 the chalk downs of the Island continued as a long range 

 across what is now sea, and on through Purbeck. A great 

 Valley must have stretched from west to east, north of 

 this line, along the course of the Frome, which runs 

 through Dorset, and now enters the sea at Poole Harbour, 

 on by Bournemouth, and along the present Solent Channel 

 a valley still much above sea level, not yet cut down by 

 rivers and the sea and down the centre of this valley a 

 river must have flowed, which may be called the River 

 Solent. It received as tributaries from the south the 

 rivers of the Isle of Wight, and others from land since 

 destroyed by the sea. There flowed into it from the 

 north the waters of the Stour and Avon, and an old river 

 which flowed down the line of what is now Southampton 

 Water. Southampton Water looks like the valley of a 

 large river, much larger than the present Test and Itchen. 

 Its direction points to a river from the north west ; and 

 it has been shown by Mr. Clement Reid that the Salisbury 

 rivers Avon, Nadder, and Wily at a former time, when 

 they flowed far above their present level continued their 

 course into the valley of Southampton Water. For frag- 

 ments of Purbeck rocks from the Vale of Wardour, west 

 of Salisbury, have been found by him in gravels on high 

 land near Bramshaw, carried right over the deep vale of 

 the Avon in the direction of the Water. The lower Avon 

 would originally be a tributary of the Solent River ; and 

 it enters the sea about mid-way between the Needles 

 and the chalk cliffs of Purbeck, just opposite the point 

 where we might suppose the sea would have first broken 

 through the line of chalk downs. No doubt it broke 

 through a gap made by the course of an old river from the 

 south, as it is now breaking through the gap made by the 

 old Yar at Freshwater. When the river Solent had been 

 tapped at this point, the Avon just opposite would have 

 acquired a much steeper flow, causing it to cut back at a 



