The adventurers and photographers Ellsworth and Emery Kolb on the Colorado river, circa 1911-12. ‘Ellsworth and Emery Kolb were the last of the Grand Canyon pioneers, and the most colorful,’ says Roger Naylor, who wrote a book about the brothers. ‘They dangled from ropes, clung to sheer cliff walls by their fingertips, climbed virtually inaccessible summits, ran seemingly impassable white-water rapids, braved the elements, and ventured into unknown wilderness – all for the sake of a photo’