Jameson stopped short of the westernmost isles, so he missed the chance to catalog the striped and mottled rock that forms the foundation of the Outer Hebrides. Named for the Isle of Lewis, where it was first described, Lewisian gneiss was born from volcanic activity deep in the crust more than three billion years ago. Intensively and repeatedly altered, lifted up by complex tectonic shifts, and revealed by massive erosion, it is the oldest rock in the British Isles and among the oldest in Europe.
Perhaps the most evocative place to encounter Lewisian gneiss is in the great stone circle at Callanish, overlooking Loch Roag on Lewis. Erected between 4,500 and 4,900 years ago, the Callanish stones may have been standing longer than the central ring at Stonehenge. Little is known for certain of the builders beyond their obvious engineering prowess, but it seems fitting that one of the earliest monuments to the human occupation of the Hebrides should have been crafted of this immensely old rock. Other standing stones dot the isles, along with Bronze Age burial cairns and stout Iron Age fortifications—most likewise built from Lewisian gneiss. The crumbling remains summon up the spirits of mighty warriors, the terror of villagers attacked from the sea, and the determination of farmers, shepherds, and fisherfolk to make their homes on the edge of the world.
The romance of these brooding ruins speaks powerfully to Michael Robson. The old tales, he says, "however extravagant and impossible at times, often have a measure of authenticity about them." Like the Enlightenment zeal for observation, the Romantic sensibility is an inheritance from the 18th century, and the Hebrides were among its touchstones. British inventiveness had fueled a nascent industrial revolution—and generated brutal levels of noise, pollution, and crowding. For an increasingly mechanized, urbanized world, nature became a refuge, a place for contemplation and inspiration with sublime power to transform emotions as well as thoughts. "Every valley has its battle, and every stream its song," declared Sir Walter Scott, whose novels and poems gave voice to wild Scotland. Even resolutely rational Robert Jameson assured readers that he was not "insensible to the emotions which naturally arise from the retired and striking scenes which often burst upon me."
The scene widely regarded as the most striking in all the isles was discovered in 1772 by English naturalist Joseph Banks. On his way to Iceland via the Hebrides, Banks had visited the diminutive island of Staffa and found in its southwest part "the most remarkable pillars." Now known to be the remains of colossal volcanic eruptions that began to tear open the North Atlantic Ocean Basin some 60 million years ago, the towering columns of basalt formed one magnificent spectacle after another as the explorer's party moved along the shore. Grandest of all was the great sea cavern Banks called the Cave of Fingal. Fingal was the hero of an epic poem that Scotsman James Macpherson claimed he had translated from verses written by an ancient Gaelic bard named Ossian—Britain's own Homer. Evoking a mythic past, the epic—eventually revealed to be largely Macpherson's composition—had ignited a romantic fascination with the misty landscapes of Britain's north.