The Grand Canyon is a gash a mile deep and 446 kilometres long across northern Arizona, cut by the Colorado River through rock that goes back two billion years, and the first thing it does is stop you at the edge. At Mather Point on the South Rim you walk out of low pines and juniper and the ground simply ends; the far rim is sixteen kilometres away, and between the two lies a landscape of buttes, terraces and side canyons in bands of red, orange and cream, with the river a thin green line at the bottom. The bands are time. Each layer is a former sea floor, desert or river delta, and near the base, sandstone half a billion years old rests directly on rock more than a billion years older, with everything in between eroded away before the upper layers were laid down.
The rim is where most people stay, and the road west along Hermit Road strings together overlooks where the canyon widens and every point frames it differently, especially when storms move through and light falls in shafts. The canyon itself begins when you go under the rim. The Bright Angel Trail, an old mule path, switchbacks down from the village, and with every bend the walls close over you, a new band of rock appears and the air gets warmer and drier; the bottom is a different climate from the top. Deeper still is the river: rafts run the Colorado through the inner canyon for days, with the rim a full mile overhead. Above the South Rim, California condors, North America's largest land bird with a wingspan near three metres, circle the cliffs on summer afternoons. On a moonless night the canyon fills with a darkness almost gone from the modern world, and the Milky Way rises in an arch straight over the void.