Those are an island of the Old World, called now the Mendip Hills; and we are steaming along the great strait between the Mendips and the Welsh mountains, which once was coral reef, and is now the Severn sea; and by the time you have eaten your breakfast we shall steam in through a crack in that coral-reef; and you will see what you missed seeing when you went to Ireland, because you went on board at night.
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Oh! Where have we got to now? Where is the wide Severn Sea?
Two or three miles beyond us; and here we are in narrow little Avon.
Narrow indeed. I wonder that the steamer does not run against those rocks. But how beautiful they are, and how the trees hang down over the water, and are all reflected in it!
Yes. The gorge of the Avon is always lovely. I saw it first when I was a little boy like you; and I have seen it many a time since, in sunshine and in storm, and thought it more lovely every time.
Look! there is something curious.
What? Those great rusty rings fixed into the rock?
Yes. Those may be as old, for aught I know, as Queen Elizabeth's or James's reign.
But why were they put there?
For ships to hold on by, if they lost the tide.
What do you mean?
It is high tide now. That is why the water is almost up to the branches of the trees. But when the tide turns, it will all rush out in a torrent which would sweep ships out to sea again, if they had not steam, as we have, to help them up against the stream. So sailing ships, in old times, fastened themselves to those rings, and rode against the stream till the tide turned, and carried them up to Bristol.
But what is the tide? And why does it go up and down? And why does it alter with the moon, as I heard you all saying so often in Ireland?
That is a long story, which I must tell you something about some other time. Now I want you to look at something else: and that is, the rocks themselves, in which the rings are. They are very curious in my eyes, and very valuable; for they taught me a lesson in geology when I was quite a boy: and I want them to teach it to you now.