Moraines

The diagram is a wide, panoramic reconstruction of a glacial valley long after the ice has mostly vanished. Two tributary valleys converge from the upper left and right, meeting in a broad, open lowland that slopes gently away. The scene is drawn from an elevated vantage point so you can see the whole landscape at once — the kind of view a geographer would use to trace how a glacier reshaped the ground beneath it.

The lower ground is the real focus. Scattered across it are drumlins: smooth, elongated oval mounds, all aligned with their long axes pointing in the same direction — the direction the former ice moved. Their parallel orientation is the key teaching point: drumlins are streamlined by ice flow, so they act like fossil compass needles for reconstructing the glacier's path. Winding across the same plain are eskers — sinuous, snake-like ridges that mark where meltwater once ran in tunnels beneath the ice. As the glacier thinned and retreated, the sediment carried by those subglacial streams was dumped in long, winding ridges that now stand above the surrounding ground.

At the far edge of the plain, a curved arc of debris is labelled terminal moraine — the ridge of till dumped at the glacier's furthest advance. Beyond it spreads the outwash plain, a fan of gravel and sand washed out from the melting ice front. Dotted across this plain are small, roughly circular depressions: kettle lakes, formed when blocks of ice buried in the outwash melted and left hollows behind. An arrow labelled outwash points away from the moraine, showing the direction in which meltwater carried sediment outward from the ice. …