Colours Of The Saône And The Rhône

[koster]

Yesterday I did a boat trip in Lyon, where the Saône and the Rhône meet. It was pointed out that the two rivers have different colours and this could clearly be seen.

Does anyone know why?

Thanks!

[woofgang]

one carries sediment from its river bed, the other doesn't.

[Buenchico]

Assuming that it's natural (rather than due to pollution) it must be because the river valleys lie across different surface geologies, so that the rivers pick up different chemical elements as their waters abrade the surfaces of the rocks over which they pass.

Switzerland and France have complex surface geologies:
https://upload.wikimedia.org/wikipedia/commons/thumb/8/8b/France_geological_map-fr.svg/2000px-France_geological_map-fr.svg.png

[mushroom25]

.......plus, the rhone rises at an alpine glacier, and carries the bluey-white milky sediment characteristic of such rivers.

[koster]

Thanks!

[Jennykenny]

Interesting Koster, am going to Lyon in the next few weeks. Will definitely do the boat trip.
Anything else I should look out for in the city??

[koster]

Hello Jenny,

I would suggest looking around the old part of town, having a leisurely lunch, wandering along the art and craft stalls by the river, and climbing the many steps to the cathedral at the top of the hill (there is also a funicular railway to get up there).

Laurence