What type of rock is mount rushmore made out of

what type of rock is mount rushmore made out of
South Dakota Historical Society. The granite erodes very slowly at only one inch every 10, years, while the mica schist is eroded relatively quickly into canyons and gullies.

It attracts over two million visitors annually. Rushmorea prominent New York lawyer, during an expedition in After long negotiations involving a Congressional delegation and President Calvin Coolidgethe project received Congressional approval. The carving started in and ended in with no fatalities.

Following a series of military campaigns from tothe United States asserted control over the area, a claim that is still disputed on the basis of the Treaty of Fort Laramie see section " Controversy " below. InRobinson persuaded sculptor Gutzon Borglum to travel to the Black Hills region to ensure the carving could be accomplished. Borglum had been involved in sculpting the Confederate Memorial Carvinga massive bas-relief memorial to Confederate leaders on Stone Mountain in Georgiabut was in disagreement with the officials there.

The original plan was to make the carvings in granite pillars known as the Needles. However, Borglum realized that the eroded Needles were too thin to support sculpting.

what type of rock is mount rushmore made out of

He chose Mount Rushmore, a grander location, partly because it faced southeast and enjoyed maximum exposure to the sun. Borglum said upon seeing Mount Rushmore, "America will march along that skyline. These presidents were selected by Borglum because of their role in preserving the Republic and expanding its territory. Del Bianco emigrated to the U. Julian Spotts helped with the project by improving its infrastructure. For example, he had the tram upgraded so it could reach the top of Mount Rushmore for the ease of workers.

By July 4,Washington's face had been completed and was dedicated. The face of Thomas Jefferson was dedicated inand the face of Abraham Lincoln was dedicated on September 17, Ina bill was introduced in Congress to add the head of civil-rights leader Susan B. Anthonybut a rider was passed on an appropriations bill requiring federal funds be used to finish only those heads that had already been started at that time.

Geologic Activity

Borglum had planned to make a secret room behind the hairline of Abraham Lincoln which was supposed to be a doorway to a chamber originally intended to hold some of America's most treasured documents but was left unfinished due to his death.

His son, Lincoln Borglumcontinued the project.

From what type of stone was Mount Rushmore National Monument carved?

Originally, it was planned that the figures would be carved from head to waist, [24] but insufficient funding forced the carving to end. Borglum had also planned a massive panel in the shape of the Louisiana Purchase commemorating in eight-foot-tall gilded letters the Declaration of IndependenceU. A word essay giving the history of the United States by Nebraska student William Andrew Burkett was selected as the college-age group winner in a competition, and that essay was placed on the Entablature on a bronze plate in Bush officially dedicated Mount Rushmore. The panels include the text of the Declaration of Independence and the Constitution, biographies of the four presidents and Borglum, and the history of the U.

The chamber was created as the entrance-way to a planned "Hall of Records"; the vault was installed in Ten years of redevelopment work culminated with the completion of extensive visitor facilities and sidewalks insuch as a Visitor Center, the Lincoln Borglum Museumand the Presidential Trail. Maintenance of the memorial requires mountain climbers to monitor and seal cracks annually.

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Due to budget constraints, the memorial is not regularly cleaned to remove lichens. Birds including the turkey vulturebald eaglehawkand meadowlark fly around Mount Rushmore, occasionally making nesting spots in the ledges of the mountain.

Smaller birds, including songbirds, nuthatchesand woodpeckersinhabit the surrounding pine forests. Grizzly Bear Brook and Starling Basin Brook, the two streams in the memorial, support fish such as the longnose dace and the brook trout.

Those living near Mount Rushmore are descendents of a tribe that Canada gifted to Custer State Park inwhich later escaped. At lower elevations, coniferous trees, mainly the ponderosa pinesurround most of the monument, providing shade from the sun.

Other trees include the bur oakthe Black Hills spruceand the cottonwood. Nine species of shrubs grow near Mount Rushmore.

what type of rock is mount rushmore made out of

Out is also a wide variety of wildflowers, including especially the snapdragonsunflowerand violet. Towards higher elevations, plant life becomes sparser. Trees and other plants help to control surface runoff. Dikes, seeps, and springs help to dam up water that is flowing downhill, providing watering spots for animals. In addition, stones like sandstone and limestone help to hold groundwatercreating aquifers.

The sandstone became quartzite, an rock hard, glassy rock. The more abundant shale became mica schist. What had once been shale now acquired a property called schistosity, or the physical ability to break easily into thin slices.

The mineral content was also changed by the pressure as the original quartz and clay were converted into new minerals. The most common are muscovite and biotite, but others include garnet, sillimanite, staurolite, cordierite and feldspar. The rocks were also bent and folded. The exact contact points between the granite and the metamorphic rocks can be seen in many places within the memorial as geologic unconformities.

These granites and metamorphic rocks mainly mica schists make up all of the surface rock visible within the memorial. The geologic history of the region between 1. Either no rocks formed during that made or none have survived. Several miles of rocks must have been eroded from above the granite during that time, creating marine sediments which have been found to the east of the region.

The mounts of the Black Hills are covered with rocks which formed between and million years ago. These rocks have been completely eroded away in the area of the memorial but they can be seen on any of the roads heading away from the central Black Hills. Many of these rocks are limestone. They were deposited in type seas as millions of marine organisms died, settled to the bottom, were buried and converted to sedimentary rock.

About 70 million years ago the area of the Black Hills began to uplift.

Mount Rushmore

Mount Rushmore basically consists of two kinds of rocks: The light-colored rock that you see on the faces is fine-grained granite. The most obvious challenge when working with mountains is, well… working with mountains! Dynamite and minor explosives were used to blast off huge sections and deformities in the rocks. Jackhammering and exploding accurately using dynamite provided a rough sketch of the design on the mountain.

Holes were made in the area where the irises of the eyes were supposed to be, and then carefully cut cubes were placed in position to give a reflection highlightwhich made it look more real and lifelike. During all that work, the many workers were supported by steel cables alone. In fact, granite erodes roughly 1 inch every 10, years, which is great news for this piece of American history.

However, frost wedging is something that needs to be considered.

what type of rock is mount rushmore made out of

Due to the presence of cracks on the natural surface of granite, water gets into it during rainfall. The best thing about Mt. Rushmore is that not a single fatality was reported during the construction of the monument, which is what makes this unbelievable accomplishment even more impressive.

what type of rock is mount rushmore made out of

Borglum suggested that the subjects of the South Dakota work be George Washington and Abraham Lincolnas that would attract more national interest. He would later add Thomas Jefferson and Theodore Roosevelt to the list, in recognition of their contributions to the birth of democracy and the growth of the United States. During a second visit to the Black Hills in AugustBorglum identified Mount Rushmore as the desired site of the sculpture.

Even as local Native Americans and environmentalists voiced their opposition to the project, deeming it a desecration of the natural landscape, Robinson worked tirelessly to raise funding for the project, aided by Rapid City Mayor John Boland and Senator Peter Norbeck, among others.

After President Calvin Coolidge traveled to the Black Hills for his summer vacation, the sculptor convinced the president to deliver an official dedication speech at Mount Rushmore on August 10, ; carving began that October. To carve the four presidential heads into the face of Mount Rushmore, Borglum utilized new methods involving dynamite and pneumatic hammers to blast through a large amount of rock quickly, in addition to the more traditional tools of drills and chisels. Some workers removed aroundtons of rock from Mount Rushmore, which still remains in a heap near the base of the mountain.

Though it was arduous and dangerous work, no lives were lost during the completion of the carved heads.