A Mountain Epic

The mountains are are made of greywacke and they are continually shedding rocks that tumble down scree fans and alpine cascades. A lot of them are bled into the great Waimakariri River which churns and tosses them, and carries them down the long gorge through the Southern Alps. By the time they reach the place where the gorge opens out to the Canterbury Plains they are rounded, and worn as smooth as greywacke gets. Then some of them are gathered up and fed into a crushing machine and turned into grit, and so a new mountain is formed.

This one has been sitting there for so long erosion is setting in. I don't know if the whole process is repeated on a miniature scale. What d'yer reckon?