River Tay
The River Tay emerges from Loch Tay at Kenmore, and flows from there to Perth which, in historical times, was its lowest bridging point. Below Perth the river becomes tidal and enters the Firth of Tay. The largest city on the river, Dundee, lies on the north bank of the Firth. On reaching the North Sea, the River Tay has flowed from west to east across central Scotland.
Moray Firth
Basically, the Moray Firth is of tectonic origin, related to the Great Glen Fault. For some time during the glaciation, the whole of nowaday's Moray firth was a huge glacier. Nevertheless, the inner Part and its side-inlets, Cromarty Firth and Dornoch Firth, are true fjords themselves. Though there is a reasonable tide with mean tide ranges of about three metres (ten feet), only part of the rivers draining into the bay have estuaries. Masses of sediment from the adjacent mountains have formed spits around several mouths. Those of River Ness and River Carron have significantly narrowed the fjords they enter.