Inverness-shire, Scotland, 2003
The horizontal lines on the hillside, just visible in the middle of the photograph, are the 'Parallel Roads' of Glen Roy. The origins of these features remained an enigma until the Swiss geologist Louis Agassiz visited the Scottish Highlands in 1840. Earlier visitors, including Charles Darwin, had believed that the parallel roads were traces of ancient sea-shores. Agassiz explained that they marked the levels of a freshwater lake, which filled Glen Roy when the outlet to Glen Spean was blocked by a glacier.
Although still parallel, the 'roads' are not quite level. Relieved of the great mass of ice, since the end of the most recent glacial period, the Scottish Highlands are still moving upwards. The land may not regain equilibrium before the end of the present interglacial period.