Trail Of The Unexpected: The face of the Black Hills

Four presidents and a native american leader

Bordering North Dakota, Montana, Wyoming, Nebraska, Minnesota and Iowa is the state of South Dakota, home to Mount Rushmore's big-headed presidents. Mount Rushmore was named after a New York lawyer in 1885 long before the monument was dreamt of. On the mountainside amid a setting of pine, spruce, birch and aspen, are giant busts of George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln.

The sculptor, Gutzon Borglum (reputedly the son of a Danish Mormon bigamist), had warmed up with a relief of Confederate General Robert E Lee on Stone Mountain in Georgia. Borglum and a team of 400 workers then began sculpting the heads of state between 1927 and 1941 (he'd intended to continue the sculpture to include the upper bodies but was 60 when he began the project and didn't live long enough to get below their necks).

The idea was to represent the first 150 years of American history: each president was chosen for his role in the nation's birth and growth. Washington to signify the struggle for independence and establishment of the Republic; Jefferson as author of the Declaration of Independence and for his role in westward expansion. Lincoln represented the preservation of the country under the Civil War and equality for all citizens, and Roosevelt was chosen for reasons including his work towards conservation.

First Borglum made 1.5m plaster models of each head; measurements were transferred to the mountain with a horizontal bar and plumb bob. The granite faces measure 18m from forehead to chin: the noses alone are 6m long. Lincoln's face has a mole (made out of the mountain) half a metre across. Cracks and fissures in the rock forced Borglum to change his design nine times. Dynamite and jackhammers were used to remove excess rock, followed by small drills, hammers and wedges to chip away at the mountain. The sculpture surface was then smoothed with air hammers.

Mount Rushmore is situated in the Black Hills, which cover an oval area of approximately 104 by 200km in western South Dakota (spilling over the state line into eastern Wyoming). Don't be put off by the sombre name: the dense covering of Ponderosa pine and Black Hills spruce look like a very dark blanket in contrast with the light colours of the surrounding meadows and prairies, and the Lakota people named them "paha sapa", "hills that are black".

In 1874 Custer led an expedition into the area and discovered gold – starting a rush. The fortune-hunters ignored a treaty that had been signed six years earlier establishing the area as part of the Great Sioux Reservation and forced the Lakota to relinquish their homelands. Mining camps sprang up throughout the hills: the more successful became towns where they still mine the precious metal.

But the countenances of some of George Bush's predecessors aren't the only great faces in the Black Hills. In 1948 Korczak Ziolkowski, a self-taught sculptor of Polish descent, began a project at the request of Lakota Chief Standing Bear, who wrote, "My fellow chiefs and I would like the white man to know the red man has great heroes, too."

Native American leaders chose their great hero Crazy Horse to be the subject for their own mountain carving: he is revered for his loyalty and tenacity of purpose, unfailing courage and skill as a warrior. Since his death in 1877 his memory has been a symbol of the American Indian spirit, pride and courage. For this, the world's largest mountain sculpture is in progress. Just before Korczak died in 1982 he asked his wife and children to continue his work.

When it's finished – because of such factors as the uncertainty of the weather and financing it's impossible to predict a completion date – the Crazy Horse carving will be 194m by 170m. The head (which has been completed) is 26m high – that is equivalent to nine storeys tall. His horse's head will be 66m, or 22 storeys, high. All four faces on Mount Rushmore would fit into Crazy Horse's head, and his arm will be almost as long as a football pitch.

President's Day, a national holiday in the US, is on Monday 17 February