I can't help thinking of the USA without conjuring up the image of a long and lanky mountain man, bearded and blue-eyed, intense in word and thought. A man who never lost his Scottish accent and, on all his travels, carried two books with him - the New Testament and the works of Robert Burns.

I would argue that John Muir was Scotland's greatest export to America, a man who emigrated to Wisconsin from Dunbar in East Lothian at the age of 11. He eventually became an all-American hero - the father of the modern ecological movement, the father of the modern conservation movement and the father of the worldwide national parks movement. And it is in that last context that John Muir came to mind as I tramped around the cliffs, the machairs and the hills of North Harris.

In good summer weather the highways and byways of the Outer Hebrides offer sensational walking opportunities. The Hushinish peninsula of Harris is typical, boasting a rich mix of landscape types made even more memorable by the immense seascapes that front them. It's this blend of land and sea that makes the Western Isles such a special place and so worth protecting. As far as I'm aware, John Muir never visited the Outer Hebrides but I have little doubt he would have been captivated by the magic of Hushinish, wandering over the cliffs and machairs that lay close to the pulsing rhythms of the sea.

Hushinish is also one of our finest examples of an environment that has resulted from its oceanic weather conditions. Machair abounds and the bays boast superb sweeps of white shell sand. The area faces the unoccupied island of Scarp, which dominates the mouth of Loch Resort. A few years ago there were as many as 50 people living there and the community had its own school. Today it's deserted.

It wasn't just the lie of the land that put me in mind of Muir. A few weeks ago, a consultation began to seek the community's opinion on commissioning a study into the potential advantages and disadvantages of national park status for North Harris. This could enhance the numerous European and UK environmental designations already in place over the island and raise the area's profile.

Muir was never slow to publicise the special qualities of an area, believing that the more people visited such areas, the more people would be prepared to lobby for their protection from unsuitable developments. I wished he had been with me as I left the pier at Hushinish and climbed over the cliffs of Rubha Ruad and Geodha Roaga. We could have climbed the grassy slopes to the summit of Cnoc Mor and surveyed the glorious scene around us. I'm sure Long John would, by now, be rhapsodising in typical Muir fashion, thrilled by the wheeling seabirds and the views of purple land and green ocean.

Later, as we travelled further inland below Husival Beag towards Loch na Cleavag, we would listen for the otherworldly call of the black-throated diver. Golden plover, wheatear, wren, rock pipits and stonechat are not uncommon and the golden eagle breeds here, a sure indication of the genuine wildness of the place.

Before leaving the lovely headland of Rubh' An Tighe, with its views of the little island of Fladday and into the narrow Loch Resort, the geographic boundary between Harris and Lewis, I sat above the old lazybeds and thought of Muir inviting President Theodore Roosevelt to spend some nights camping below the pines of Yosemite with him, to show the politician the wonders of the place and what could be lost if the area wasn't protected by legislation. Roosevelt was so impressed he began drawing up plans for what is now Yosemite National Park.

I often wonder if things would have been different in Scotland had Muir never left. Would we be better protected against commercial developments that ignore the cultural, scenic and wildlife qualities that bring tens of thousands of visitors here? I like to imagine Muir inviting First Minister Alex Salmond to come and sit here, to gaze and to wonder and enjoy the natural beauty of the place. Perhaps it's not too late for the spirit of Muir to have an impact on North Harris's future. fact file

Map: OS Sheet 13 Distance: About 6 miles Approx time: 4-5 hours Start/finish: The pier at North Hushinish. This can be reached by car by a long, single-track road, which turns off the A859 two miles north of Tarbert.

Route: Leave the pier and follow the coast west then south, crossing a fence by a stile. Stay above the low cliffs of Rubha Ruadh then follow a zig-zagging path to the cliff-tops above Geodha Roaga. Head east and climb grassy slopes to the summit of Cnoc Mor. Descend east towards Hushinish Bay and turn north to reach a gate just before Huisinis. From here a track will take you back to Hushinish pier.

The second part of the walk goes north of the pier road and through a gate. A path now follows the foot of the cliffs above two small ravines before dropping down again to a low pass south of Gresclett. Go right now to Loch na Cleavag and then along the loch's east shores to the headland of Rubh' an Tighe. Left now, cross the headland and drop down to Traigh Mheilein. Follow the beach to its southern point and join a track up the side of Gresclett to rejoin the path you followed earlier. Follow the path back to the pier.