the pebbles will be in the lower course of a river. the pebbles will be in the lower course of a river.
The upper course is usually in the mountains and is where its source is, it is where most rivers have waterfalls and gorges. It also has small meanders and a v shaped valley.
Meanders, Ox-bow lakes, Levees, floodplains, deltas or estuaries..... :)
the waterfall is in the upper course
In the lower course of a river , it is shallow and not very deep at all.