River Tay
Location: 56N 4E (Scotland); length 188 km; drainage basin: 9600 sq km

The River Tay is Scotland's longest river. It rises in the Scottish Highlands and flows swiftly eastwards to the Firth of Tay at Perth. Dundee lies on the northern banks of the Firth of Tay, using the shelter of the estuary as the basis of an important natural harbour, serving trade in the North Sea.

Loch Tay, a ribbon lake whose deep basin was scoured out by glaciers during the last Ice Age, lies along the route of the river. This is one of Britain's largest freshwater lakes and a favourite place for salmon fishermen.

Upper Tay
The Tay gathers its waters from a number of sources among the Grampian Highlands. The most southerly of the headwater rivers begins on the northern flanks of Ben More, then tumbles down at the Falls of Dochart into Loch Tay. Nearby, the River Lochay similarly falls over a band of hard volcanic rocks to form the Falls of Lochay. Further north more headwaters in the heart of the Grampians fill another set of glacially scoured valleys to form Loch Lyon and Loch an Daimh. The River Lyon flows from these Lochs and joins the Tay just below Loch Tay.

Loch Lyon, Loch Daimh and Loch Tay are all formed in valleys eroded from softer rocks that are aligned in a southwest to north east direction. It is only where the River Tummel enters the Tay just south of Pitlochry that the Tay begins to flow across this 'grain' od the landscape, first to Dunkeld, then to Meikleour, and finally to Perth

Lower Tay
The Tay enters Strathmore through the Pass of Birnam near Dunkeld. Strathmore is a broad vale of soft Old Red Sandstone rocks some 80 km long.The lower Tay and its tributaries lie in these soft rocks.

The Romans were the first to settle on the lower Tay, founding a number of settlements including a signal station where the Tay and Isla join.

In this broad strath, the Tay picks up both the Isla and Almond waters, before cutting through the band of volcanic rocks that make the gap were the city of Perth was founded.

The narrow gap of the Tay, cut between the Ochils and the Sidlaws, is a parallel to the site of Stirling on the River Forth. Perth was the lowest bridging point on the Tay, making it an important market centre.

The cataracts and rapids of the river near Perth made the river unnavigable, but provided something that people could make use of equally well - water power. The rapids, such as Linn of Campsie near Stanley, are the places where there are sheets of hard volcanic rock in the sandstone. Here the Tay provided an impressive head of water to drive water mills in the early days of the Industrial Revolution.

The swift waters of the river were first used for flour milling. In addition, the softness of the water made the river very suitable for bleaching and dyeing cloth, and thus using river power at first and steam later, Perth developed as a centre for the textile industry. The softness of the water was also ideally suited to the making of whisky, which is why the whisky distilleries moved to places like Perth and Pitlochry.

The Tay is also famous for the collapse of the Tay railway bridge in 1879. This enormously long bridge went across the estuary, close to where its replacement can be seen today.