The river-bed has pebbles smooth –
Some like pan-cakes; no two alike;
The river water sculpted all
With beauty, human machines can’t!

They vary in their hues and size,
And look like cobble-stones, half-laid;
How many years of Nature’s toil
Have made the rocky floor look thus!

They shift and turn when water comes,
And travel like the UFOs,
Down river, as the waters flow,
In harmony with river’s drift.

Dr John Celes

http://www.poemhunter.com/poem/awesome-pebbly-river-bed/