Glasgow’s Ice Age Landscape

Anyone who has walked up Gardner Street in Partick, or climbed from Sauchiehall Street to the top of Garnethill, knows that Glasgow is a city of short, steep hills. They are not random. Much of Glasgow is built on a swarm of drumlins, smooth oval hills of clay and stones moulded by glaciers during the last Ice Age. The shape of the land they created has influenced where people settled, how streets were laid out and even where some of the city’s best known buildings stand.

The rocks beneath the city

Long before the Ice Age, the rocks under Glasgow were laid down more than three hundred million years ago, in the Carboniferous period, when this part of the world lay near the equator and was covered at different times by tropical swamps, river deltas and shallow seas. Those environments left layers of sandstone, shale, limestone, coal and ironstone. They would matter enormously much later: the coal and ironstone fuelled the city’s industrial revolution, as described on our coal and iron pages, and the sandstone quarried in and around Glasgow built its tenements and public buildings. Volcanic rocks of a similar age form the hills that ring the city to the north, including the Campsie Fells and the Kilpatrick Hills.

The ice

Over the last two and a half million years Scotland was repeatedly covered by ice. During the last major glaciation, ice sheets hundreds of metres thick spread out from the Highlands and flowed across the lowlands of the Clyde valley. As the ice moved, it scraped and ground the rocks beneath it and carried enormous quantities of clay, sand and boulders. This mixture, called till or boulder clay, was smeared across the land beneath the moving ice.

The ice sheet melted away around fifteen thousand years ago. There was a final cold snap, when glaciers advanced again in the Highlands and reached the southern end of Loch Lomond, before the climate warmed for good around eleven and a half thousand years ago. The landscape the ice left behind is the one on which Glasgow was later built.

A swarm of drumlins

In many places the moving ice moulded the till into drumlins: rounded, elongated hills, shaped a little like half an egg lying on its side, with their long axes pointing in the direction the ice was flowing. Drumlins often occur in large groups, creating what geographers call basket of eggs landscape. The lower Clyde valley contains one of the best known drumlin swarms in Britain, and Glasgow sits right in the middle of it.

Once you know to look for them, the drumlins are everywhere. Several of the city’s best known hills, such as Garnethill, Blythswood Hill and Partickhill, are usually described as drumlins, and the slopes of the West End are full of them. Gardner Street in Partick, which runs straight up the side of a drumlin, is often described as one of the steepest streets in the city. A study of Glasgow’s drumlins noted that there are at least sixteen streets in the Glasgow area simply called Hill Street. Not every hill in Glasgow is a drumlin, though: some, like the ridge on which the Necropolis stands, have a different origin.

Shaping the city

The drumlins influenced Glasgow’s development in many ways. Their dry, well drained tops were attractive places to build, while the wetter hollows between them often held burns and marshes. When eighteenth and nineteenth century developers laid out the new town on Blythswood Hill, described on our William Harley page, they set a rigid grid of streets over the drumlin regardless of its slopes, which is why so many city centre streets climb so steeply. Grand terraces and churches were placed on the crests, where they could be seen from afar, as at Park Circus and on Gilmorehill, where the University of Glasgow moved in 1870.

The clay between the drumlins also mattered. It made the ground heavy and slow to drain, and it was used for brickmaking. In the twentieth century engineers digging tunnels and foundations, including for the Glasgow Subway, had to deal with the varied mixture of clay, sand, gravel and boulders left by the ice.

The river after the ice

As the ice melted, sea levels and the land itself both changed. Freed from the weight of the ice, the land slowly rose, while meltwater raised the level of the sea. For a time the sea reached further up the Clyde valley than it does today, and old shorelines and beach deposits, known as raised beaches, were left along the lower valley. The flat ground beside the river, on which much of the riverside city was built, owes a great deal to these deposits and to the sands and gravels laid down by the river.

The Clyde itself remained wide and shallow, with sandbanks and fords, until engineers began deepening it in the eighteenth century, as described on our Clyde deepening page. People had lived beside it since long before the first written records, and the evidence of those early inhabitants is described on our Glasgow before the Romans page.

Seeing the Ice Age today

The easiest way to see Glasgow’s Ice Age landscape is to look at the skyline from a high point, such as the Necropolis or the top of a tall building, and notice how the city rises and falls in a series of rounded humps. Walk up any of the city’s Hill Streets, or climb Gardner Street, and you are walking up the side of a hill made by a glacier more than ten thousand years ago.

Timeline