Mount Rushmore National Memorial / A monument commemorating the conception, preservation, and growth of the great American republic

by Mount Rushmore National Memorial Society of the Black Hills

DEVILS TOWER NATIONAL MONUMENT

Another unusual natural phenomenon of the Black Hills country is the Devils Tower across the South Dakota state line in Wyoming. This is a great column of igneous rock towering 1,280 feet above the Belle Fourche river, whose course is near the base. Devils Tower has the distinction of being the first national monument created under the Antiquities Act of 1906. It was established by proclamation of September 24 of that year, by President Theodore Roosevelt.

Devils Tower in Wyoming’s western border of the Black Hills National Forest.

THE ANTIQUITY OF MOUNT RUSHMORE
By the late JOSEPH P. CONNOLLY
President, South Dakota School of Mines

At the Battle of the Pyramids, Napoleon is reported to have exhorted his men by saying, “Soldiers, from these pyramids forty centuries look down upon you.” From the standpoint of human history four thousand years represent great antiquity indeed. But as one gazes upon the rugged slopes of Mount Rushmore, he is face to face with antiquity beside which the age of the Egyptian pyramids seems but a moment.

How old is the granite of Rushmore? We have a yardstick by which we can measure that quite accurately. Not far from the mountain, in a subsidiary mass of granite, there was found a few years ago a small piece of coal-black, lustrous mineral known as pitchblende or uraninite, of which the chief constituent is the heaviest known element, uranium. We know that uranium continually undergoes atomic disintegration, changing at a slow, but uniform and measurable rate into lighter elements. The end product of this change is the metal lead. If we submit the specimen of pitchblende to chemical analysis, determine how much lead it contains, how much uranium is still left, it is a comparatively simple calculation to determine from the known rate of change, the number of years that have elapsed since the pitchblende came into existence. That experiment has been performed and the result is one billion four hundred and sixty-five million (1,465,000,000) years. Bear in mind that this enormous figure represents the time that has elapsed since the molten rock came to rest at some depth under the surface of the earth, and cooled sufficiently to crystallize into granite. It represents the age of the solid granite.

But, although the granite of which the mountain is composed dates back to a period almost inconceivably remote, Mount Rushmore itself is much younger. We know that all of the granite mountains of the southern Black Hills were carved out of the rocks by the process of erosion. Field evidence indicates that fairly early in the Tertiary period, approximately thirty million years ago, erosion had carved out the topography of the Black Hills into much the same stage as we see it today. Perhaps Mount Rushmore was not fully born in that period; its form may not yet have been completely sculptured under the chisel of time, but we know that its age must be measured in millions of years and not in centuries.

Mount Rushmore is a child of weathering and erosion. They brought the mountain into being and gave it form. But those relentless parents will not be content to leave their child as they fashioned it. They will continue their work of disintegration on the surface of the rock and along the cracks, until eventually they will completely destroy the mountain they formed, and long before the mountain will have been destroyed, the magnificent carvings of man will disappear. “How long,” we anxiously ask, “will the carvings endure?” Two processes will tend eventually to destroy the memorial, chemical weathering and physical disintegration.

A typical view from the Needles highway with the Cathedral Spires in the background.

Fantastic formations in the Badlands. The variegated coloring is at its best in the early morning or the late evening.

Chemical weathering will take place very slowly, so slowly that if it were the only destructive process we had to consider, we could with some confidence say that the memorial would endure for hundreds of thousands of years. And the progress of chemical weathering will probably be impeded by the sculpturing of the memorial, for on the figures the rock will be smoother, water will drain off more rapidly instead of penetrating, lichens and other vegetation will not have as secure a foothold as on the natural face of the rock, and thus will not contribute to so great an extent their destructive acids to such waters as do penetrate.

Physical disintegration is somewhat more to be feared. This operates in two ways, by exfoliation due to changes in temperature, and by frost action. Differential stresses set up by unequal expansion and contraction, owing to the poor heat conductivity of granite, tend to spall off or exfoliate the surface layers of rock.

When water gets into the cracks and pores of the rocks and freezes, it exerts an enormous pressure, a pressure that will spall off flakes and blocks of rock. The artist and his associates, fully aware of this hazard, have guarded against it. All cracks and fissures have been carefully avoided in the sculpturing so far as is possible. Such as have been impossible to avoid are being sealed to prevent the ingress of water, thus inhibiting to a very large extent both frost action and chemical weathering.

We have traced in part the geological history of the Mount Rushmore region, hoping that by learning something of its past we may predict something of its future. We see the hazards to which the memorial is exposed. We must frankly recognize them and guard against them so far as possible, as it would be folly to ignore them. If the science of geology can do no more in a practical way for mankind than to point out dangers and sound warnings, it does a worth while service. “How long will the memorial last?” Geology cannot answer specifically. An eminent geologist has already given as definite an answer as it is possible to give, and I can do no better than to close by quoting from the address given by the late Dr. C. C. O’Harra at the unveiling of the head of Washington.

“How long will Mount Rushmore last? Many millions of years. The number nobody knows. How long will endure this monumental, sculptured figure of the Father of our Country which today we unveil? One hundred years? Yes. One thousand years? Yes. A hundred thousand years? In all likelihood, yes. A half million years? Possibly so, nobody knows. The time at any rate will be long, far longer than we can readily comprehend. And this doubtless will abundantly suffice.”

THE HALL OF RECORDS AND GREAT STAIRWAY
By LINCOLN BORGLUM

The Hall of Records and Stairway have been part of the Memorial plan from the beginning and are provided for in the so-called “Rushmore Bill” of 1938. A good start has been made in the carving of the Hall, which already has been excavated to the extent of seventy feet. Great care has to be exercised in the use of dynamite in carving this hall, as in carving the faces on the mountain, not to injure the stone which is to remain. Careless explosions of large amounts of powder might crumble the walls.

The Hall is located about two thirds of the way up to the mountain: the entrance to it is in a small gorge or canyon, cut by the ice aeons ago, to the right of the carved faces as one looks at them from below. The Hall is on the opposite side of the gorge from the heads and is not under them. The following is quoted from Mr. Borglum’s plan.

“The façade to the Hall’s entrance is the mountain wall 140 feet high; supporting pylons, cut into the mountain, flank the entrance. The entrance door itself is 12 feet wide and 20 feet high; the walls are plain, dressed granite and of a fine color. I want to finish the inner entrance wall in mosaic of blue and gold lapis. The depth to the door entrance from the outer façade is 20 feet. The door, swung on a six inch offset of the wall, will be of bronze and glass. Small, carefully modeled bronze figures of historic importance from Columbus and Raleigh to the present day will ornament the doors or be modeled into the supporting frame. The walls of the entrance will carry in gilded bronze immediately within the entrance ancient Indian symbols; British, French, Spanish and American seals.

“The floor of the Hall will be 100 by 80 by 32 feet to an arched ceiling. At the height of fifteen feet an historic frieze, four feet wide, will encircle the entire room. Recesses will be cut into these walls to be filled with bronze and glass cabinets, which will hold the records stamped on aluminum sheets, rolled separately and placed in tubes. Busts of our leaders in all human activities will occupy the recesses between the cabinets. The original thought of a hall of human records I developed at Stone Mountain in Georgia and my drawings and full plans are extant; that was never completed.

“The records of electricity, beginning with Franklin, which has given us light, heat, music, the radio, the telegraph, the telephone and controls in power the extent of which we can hardly imagine, must be here, together with the records of literature, the records of travel, immigration, religious development and also the record of perhaps the largest contribution that we have made to humanity, which has been free controlled peace, a government of the people, by and for the people. Struggle as we will that great contribution is today the cause for the real unrest of Europe. Despotism, tyranny of every form is fighting us wherever it can, to take away from humanity the power freedom gives it—the power that freedom has given America.

Opening of a gorge reached by the Great Stairway is the massive twenty-foot-high entrance to the Hall of Records.

“The Hall will be reached by a monumental flight of steps varying from 15 to 20 feet in width, which will ascend the mountain in front, a little to one side of the sculpture, rising from a great granite disk or platform in the canyon below, which may be used as a rostrum from which speakers may address the public occupying the amphitheater facing the great group.

This picture shows the workmen busy in the early stages of the work of carving the Hall of Records from the granite.

“These steps of granite and cement will be provided with seats at intervals of every fifty feet; they will have a five inch rise and an eighteen inch tread. The ascension from the foot of the steps to the floor of the great entrance is four hundred feet; the entrance way from the steps’ landing to the great Hall is 190 feet; the floor of this Hall, reached by three steps, is two feet above the floor of the entrance way in the canyon; this to provide for proper drainage.”

Owing to repeated requests from important organizations of women, the urging of some senators and congressmen and Mr. Borglum’s own realization of the part women have played in the development of our country, plans had been under way for some years to include women in the great Shrine of Democracy. There was no room in the rock which contains the heads of the four presidents and the only other place seemed to be the west wall of the granite cliff, or in the hall of records. To quote again from Mr. Borglum, from a letter written in January 1940: “If we decide that the west side of the mountain is suitable, I am for it. We must work out a design that is fitting and in no sense harmful in the matter of lighting or location to subjects determined upon and I am entirely in favor of carving the faces of two or three women. If that is determined upon, these figures will be near what has been known in the Rushmore Law as the Inscription and there will be a special paragraph given to the work and services of women. The original inscription referred to the framing of the Declaration of Independence; that was Jefferson’s work and the second was the Constitution. That was Washington’s greatest service. The third dealt with the purchase of the Louisiana Territory and the fourth, fifth, and sixth, the progress towards the south and southwest, involving Florida, Texas and California, which included Arizona, a portion of Nevada, Utah and a portion of Idaho. The seventh paragraph brought in the Oregon cession from England and the purchase of Alaska. There was one paragraph for Lincoln and one for the finishing of the Panama Canal, which was achieved by Theodore Roosevelt.

The corridor leading from the doorway into the Hall of Records, showing the marks of the stonecutters’ tools.

“So by these suggestions you will see that a splendid paragraph can be developed for the part women have played in the development of the nation.” In another part of the letter Mr. Borglum made a place for women in the Hall of records and even suggested that a special hall might be carved for them, as there is ample rock for many rooms.

Calvin Coolidge had been asked to collaborate on the inscription and wrote the first two paragraphs. Mr. Borglum stood strongly for “Justice” in the wording, whereas Mr. Coolidge insisted upon “Justice under the Law.” Newspaper accounts exaggerated the discussion, which unfortunately was terminated by Mr. Coolidge’s death.