But what has this to do with a gravel-pit?

This first.  That all the flints in this pit have come out of the chalk.  They are coloured, most of them, with iron, which has turned them brown; but they are exactly the same flints as those gray ones in the chalk-pit on the other side of the town.

How do I know that?

I think our own eyes will prove it:  they are the same shapes, and of the same substance; but as a still surer proof, we find exactly the same fossils in them; sponges, choanites (which were something like our modern sea-anemones), corals, and “shepherds’ crowns” as the boys call the fossil sea-urchins.  The species of all these, and of other fossils, in the chalk-pit and in the gravel-pit, are absolutely identical.  The natural conclusion is, then, that the gravel has been formed from the washings of the chalk.  The white lime of the chalk has been carried away in water by some flood or floods; the heavier flints have been left behind.

Stop now one moment, and think.  You all know how very few flints there are in the chalk-pit, in proportion to the mass of chalk.  You all know what vast gravel-beds cover the country to the north, and often to the thickness of many feet.  Try and conceive, then, what a much more vast mass of chalk must have been washed away, to leave that vast mass of gravel behind it.—­Conceive?  It is past conception.  I will but give you two hints as to its probable size.

The chalk to the eastward, between here and Farnham, is a far narrower and shallower band than anywhere else in England.  Its narrowest point is, I believe, beneath the bishop’s palace at Farnham, where it may be a hundred feet thick, instead of several hundred, as it usually is in other parts of England.  The cause of this is, that the whole of the upper chalk has been washed away, to form the gravel-beds to the north and east of us.

Again.  Some of you may have been on the Hind Head or on Leith Hill, and have looked southward over the glorious prospect of the rich Weald, spread out five hundred feet below—­a sight to make an Englishman proud of his native land.  Now, the mass of chalk which has been carried away began behind you, at the Hogsback, and the line of chalk-hills which runs to Boxhill, and stretched hundreds of feet above your head as you stand on Hind Head or Leith Hill, right over the old Weald of Sussex to the chalk of the South Downs.  And out of the scourings of that vast mass of chalk was our gravel-pit made.

Of that, and also of the Hind Head sands below it.

For you will find a great deal of sharp sand in our gravel-pits, which has not, I believe, come from the grinding of chalk flints; for if it had been ground, it would not be the sharp sand it is; the particles would be rounded off at the edges.  This is probably sand from the Hind Head; from what geologists term the greensands, below the chalk.