Why, there to the left.

There are high hills there now, as well as to the right.  What are they?

Chalk hills too.  The chalk is on both sides of us now.  These are the Chilterns, all away to Ipsden and Nettlebed, and so on across Oxfordshire and Buckinghamshire, and into Hertfordshire; and on again to Royston and Cambridge, while below them lies the Vale of Aylesbury; you can just see the beginning of it on their left.  A pleasant land are those hills, and wealthy; full of noble houses buried in the deep beech-woods, which once were a great forest, stretching in a ring round the north of London, full of deer and boar, and of wild bulls too, even as late as the twelfth century, according to the old legend of Thomas a Becket’s father and the fair Saracen, which you have often heard.

I know.  But how are you going to get through the chalk hills?  Is there a tunnel as there is at Box and at Micheldever?

No.  Something much prettier than a tunnel and something which took a great many years longer in making.  We shall soon meet with a very remarkable and famous old gentleman, who is a great adept at digging, and at landscape gardening likewise; and he has dug out a path for himself through the chalk, which we shall take the liberty of using also.  And his name, if you wish to know it, is Father Thames.

I see him.  What a great river!

Yes.  Here he comes, gleaming and winding down from Oxford, over the lowlands, past Wallingford; but where he is going to it is not so easy to see.

Ah, here is chalk in the cutting at last.  And what a high bridge.  And the river far under our feet.  Why we are crossing him again!

Yes; he winds more sharply than a railroad can.  But is not this prettier than a tunnel?

Oh, what hanging-woods, and churches; and such great houses, and pretty cottages and gardens—­all in this narrow crack of a valley!

Ay.  Old Father Thames is a good landscape gardener, as I said.  There is Basildon—­and Hurley—­and Pangbourne, with its roaring lasher.  Father Thames has had to work hard for many an age before he could cut this trench right through the chalk, and drain the water out of the flat vale behind us.  But I suspect the sea helped him somewhat, or perhaps a great deal, just where we are now.

The sea?

Yes.  The sea was once—­and that not so very long ago—­right up here, beyond Reading.  This is the uppermost end of the great Thames valley, which must have been an estuary—­a tide flat, like the mouth of the Severn, with the sea eating along at the foot of all the hills.  And if the land sunk only some fifty feet,—­which is a very little indeed, child, in this huge, ever-changing world,—­then the tide would come up to Reading again, and the greater part of London and the county of Middlesex be drowned in salt water.

How dreadful that would be!