A 'little' ice, gravel, and water - River Terraces
River Terraces are 'stepped' gravel banks, roughly parallel to, and standing some distance back from an existing river bank.
River Terraces are formed in 3-stages (1) a glacier bulldozes the glen creating the classic U-shaped glen (2) in the de-glaciation period a significant 'flood' of water, and suspended gravel flows down the glen. When the flow of water drops, the gravel drops out, and is deposited across the floor of the glen, frequently many yards deep (3) in the post-glacial period - natural river floods (a fraction of the size of the de-glaciation period floods) cut down through this gravel, creating the river terraces, and the lower flood plains we see today.
Among the most obvious river terraces in the Cairngorms is in Gleann Gheallaidh a little upstream from Ruighe Ealasaid - a typical river terrace of the Cairngorms, steep sided, several yards high, and standing several-dozen yards back from the present riverbank of Uisge Gheallaidh, while roughly paralleling it's course. The fact that the river terrace in Gleann Gheallaidh is significantly higher than other river terraces in other glens may be accounted for by the fact that the headwaters of the present day Uisge Feithisidh once flowed down Gleann Gheallaidh rather than Gleann Feithisidh.