Yes you r right but the season in which you visit that matters.if all the rocks are submerged in the river then the rock is there as bank and it's a long distance to walk.u can't find all the marbles merged in the river,what they sell they get from other locations.thats not from the same place river rocks being used for artefacts and mementos.visit in winter which is a best season for all prime locations down the altitude to see..summer is best for high altitude and sea beaches.please plan visit in these season to enjoy fully and each n everything about the place will come in to your eyes forever.

The Narmada is a perennial river and the water at Bhedaghat is hundreds of feet deep so you can still have the boat ride and admire the marble cliffs. Summer is not my favourite season to travel and day temperature in those parts will be in mid 40's. But if it cannot be avoided, go for it! Try going to the ghat early in the morning and see if you can find a boat man or late in the afternoon.