Roadcut

Roadcuts are the geologist's best friend. This tilted slate near Lake Isabella, California, is exposed in luscious detail in the roadcut whereas only a few stone spikes crop out of the hillside above it. The widespread development of modern roads has been a bonanza for students of geology.

Without roadcuts, things are much tougher. Natural outcrops include stream beds, cliffs of various kinds, caverns and heavily eroded terrain. Soil and vegetation cover the rest, especially the softer rocks. And natural outcrops are usually weathered, obscuring the rock's true character (see the greenstone page for an example). Artificial exposures in mines and quarries are useful, but these are scattered and few.

There's a reason why geology arose along with industrial technology. William Smith could create his Geological Map of 1815, the world's first, only because his business was digging canals everywhere in Great Britain. The rise of railroads and paved roads laid open the landscape like a scalpel, making mapping immeasurably easier. When you can study one perfect roadside exposure, you can recognize the rock elsewhere even when only bits and pieces stick above the soil.

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