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Great Pyramid of Giza

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The Great Pyramid of Giza (29°58′41″N 31°07′53″E / 29.97806°N 31.13139°E / 29.97806; 31.13139) is the oldest and last remaining of the Seven Wonders of the World. It is generally believed the Great Pyramid was built as the tomb of Fourth dynasty Egyptian king Khufu (also known under his Greek name Cheops and believed to have reigned from 2606-2583 BC), after whom it is sometimes called Khufu's Pyramid or the Pyramid of Khufu. Traditionally, the architect of the pyramid was HemInwo, a relative of Khufu.

The Great Pyramid

Age and location

Believed by mainstream egyptologists to have been constructed in approximately 20 years, the most widely accepted estimate for its date of completion is c. 2580 BC. The Great Pyramid is the oldest and largest of the three pyramids in the Giza Necropolis adjacent to the outskirts of modern Cairo, Egypt in Africa. Alternative theories suggest the Great Pyramid and the Giza complex date to a much earlier time period, long before pharonic Egyptian civilization.

A few hundred metres southwest of Khufu's Great Pyramid lies the slightly smaller Pyramid of Khafre, one of Khufu's successors who is believed to have built the Great Sphinx, and a few hundred metres further southwest is the Pyramid of Menkaure, Khafre's successor, which is about half as tall. Khafre's pyramid appears the tallest on some photographs as it is somewhat steeper and built on higher terrain.


File:PyramidDatePalms.JPG
Great Pyramid of Giza from a 19th century stereopticon card photo.

Construction

At construction, the Great Pyramid was 280 Egyptian Old Royal Cubits tall (146.5 metres or 481 feet), but due to erosion and the theft of its topmost stone (the so-called pyramidion) its current height is 455.21 ft, approximately 138.75 m. As has been proven by papyrus documents, each base side measured in antiquity 440 (20.63-inch) royal cubits. Thus, the Great Pyramid base was originally 231 m on a side and covered approximately 5.3 hectares. Today each side has an approximate length of about 230.36 meters, well within the precision of that measurement. The reduction in size and area of the structure into its current rough-hewn appearance is due to the absence of its original polished casing stones, some of which were up to two and a half meters thick.

In the 14th century (1301 AD) a massive earthquake loosened many of the outer casing stones of which much was carted away by Bahri Sultan An-Nasir Nasir-ad-Din al-Hasan in 1356 in order to build mosques and fortresses in nearby Cairo; the stones can still be seen as part of these structures to this day which corroborates written accounts of the time. Later explorers reported massive piles of rubble at the base of the pyramids left over from the continuing collapse of the casing stones which were subsequently cleared away during continuing excavations of the site. Nevertheless, many of the casing stones around the base of the Great Pyramid can be seen to this day in situ displaying the same uncanny workmanship and precision as has been reported for centuries.

For four millennia it was the world's tallest building, unsurpassed until the 160-metre tall spire of Lincoln Cathedral was completed c. 1300 AD. The accuracy of Pyramid's workmanship is such that the four sides of the base have a mean error of only 50 mm in length, and 12 seconds in angle from a perfect square. The sides of the square are uclosely aligned to the NSEW four compass points to within 3 minutes of arc. These alignments are based on (not magnetic north, but) true north. The rise of the sides is sometimes assumed to be 51°51', but mainly only by die-hard 'pi' adherents. For example, the Petrie survey found the South face slope to be (not 51°51', but) 51°57'30", and the other sides vary, also. In general, Petrie estimated the Great Pyramid sides at 51°50'40" ± 1'05".

Kate Spence, an Egyptologist at the University of Cambridge, has sugests the pyramids were built using as references two stars, b-Ursae Minoris and z-Ursae Majoris. This stars were in perfect aligment with the north perfect around 2467 BC. Inaccuracies in the orientations of earlier and later pyramids can be closely correlated with the degree to which the alignment of the two aforementioned stars deviates from true north.

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Khafre's Pyramid. Unlike the Great Pyramid, Khafre's Pyramid has some of its smooth outer casing limestones intact.

The pyramid was constructed of cut and dressed blocks of limestone, basalt or granite, weighing two to four tonnes on average, the biggest are in the base and decrease their size in the top. Most of the inner core was limestone, since it was easyly cut, some sections, like the shaft were build on thoughter stone. Also the portcullis used to block the pasages were made of granite. Some of the stones in the outer casing weigth up to 15 tonnes. The biggest granite stones are the five slabs that cover the relieve chambers, with an estimated weight of 60 to 80 tonnes. This was nowhere near the capacity of egyptians, since some obelisc weight up to 900 tones. This was probably the upper limit of preindustrial technology. There are speculations about the need of five relieve chambers, since a modern computer analysis indicates they are not needed, but egyptians could not know this and after the cracks in the chambers of the bent pyramid, and the colapse of the Meidum pyramid they probably decided to take extra measures.

Total mass is estimated at 5.9 million tonnes. Volume of the pyramid (including an internal hillock) is believed to be 2,600,000 cubic metres. The Great Pyramid, the largest in Egypt and tallest in the world, is surpassed only by the Great Pyramid of Cholula in Puebla, Mexico, which, although much lower in height, occupies a greater volume.

At original finishing, the Great Pyramid was surfaced by 'casing stones' – slant-faced, but flat-topped, blocks of highly polished stone. These caused the building to shine brightly in the sun, and visible from mountains in the south of Egypt as far away as 200 miles (322 km), due to its perfectly smooth sides -- sadly, for the most part now gone. Visibly all that remains is the underlying step-pyramid core structure seen today. The casing stones of the Great Pyramid and Khafre's Pyramid (constructed directly beside it) were cut to such optical precision as to be off of true plane over their entire surface area by only as little as 1/50th of an inch. These casing stones fit together so perfectly that the tip of a knife cannot be inserted between the joints along any edge. Interestingly, legend has it that light reflected by the highly polished encasement of either or both the Great Pyramid and Khafre's Pyramid could be seen miles away, even under moonlight, undoubtedly often a life-saving beacon or land marker to any lost traveller in its sight.

The Great Pyramid differs in its internal arrangement from the other pyramids in the area. The greater number of passages and chambers, the high finish of parts of the work, and the accuracy of construction all distinguish it. The walls throughout the pyramid are totally bare and uninscribed, but there are inscriptions — or to be more precise, graffiti — made by the workers on the stones before they were assembled. All the five relieving chambers are inscribed. The most famous inscription is one of the few that mentions the name of Khufu; it says "year 17 of Khufu's reign". Although believers of alternative theories have tried to declared false, the inscription could not have been made after the contruction of the chamber; even [Graham Hancock] accepted this, after Dr Hawass let him examine the inscription. Another inscription refers to "the friends of Khufu", and probably was the name of one of the gangs of workers.

There are three chambers inside the Great Pyramid. These are arranged centrally, on the vertical axis of the pyramid. The lowest chamber is cut into the bedrock upon which the pyramid was built. This chamber is the largest of the pyramid's three, but totally unfinished, only rough-cut into the rock.

The middle chamber, or Queen's Chamber, is the smallest, measuring approximately 5.74 by 5.23 metres, and 4.57 metres in height. Its eastern wall has a large angular doorway or niche, and two narrow shafts, about 20 centimeters wide, extending from the chamber to the outer surface of the pyramid, but blocked by limestone "doors" at several points. Egyptologist Mark Lehner believes that the Queen's chamber was intended as a serdab—a structure found in several other Egyptian pyramids—and that the niche would have contained a statue of the interred. The Ancient Egyptians believed that the statue would serve as a "back up" vessel for the Ka of the Pharaoh, should the original mummified body be destroyed. The true purpose of the chamber, however; remains a mystery.[1]

At the end of the lengthy series of entrance ways leading into the Pyramid interior is the structure's main chamber, the King's Chamber. This Chamber was originally 10 x 20 x 5V5 cubits, or about 17 x 34 x 19 ft, roughly a double cube.

Labor

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RJ or RL-shaped supports possibly used to raise several-ton stone blocks.

Many varied estimates have been made regarding the labor force needed to construct the Great Pyramid. Herodotus, the Greek historian in the 5th century BC, estimated that construction may have required the labor of 100,000 slaves for 20 years. Polish architect Wieslaw Kozinski believed that it took as many as 25 men to transport a 1.5-ton stone block; based on this, he estimated the workforce to be 300,000 men on the construction site, with an additional 60,000 off-site. 19th century Egyptologist William Flinders Petrie proposed that the labor force was largely composed not of slaves but of the rural Egyptian population, working during periods when the Nile river was flooded and agricultural activity suspended. Egyptologist Miroslav Verner posited that the labor was organized into a hierarchy, consisting of two gangs of 1000 men, divided into five zaa or phyle of 200 men each, which may have been further divided according to the skills of the workers.

Some research suggests alternate estimates to the aforementioned labor size. For instance, mathematician Kurt Mendelssohn calculated that the labor force may have been 50,000 men at most, while Ludwig Borchardt and Louis Croon placed the number at 36,000. According to Verner, a labor force of no more than 30,000 was needed in the Great Pyramid's construction.

A construction management study carried out by the firm Daniel, Mann, Johnson, & Mendenhall in association with Mark Lehner and other egyptologists(JUNE 1999 CIVIL ENGINEERING MAGAZINE), estimates that the total project required an average workforce of 13,200 persons and a peak workforce of 40,000 and was completed from start to finish in approximately 10yrs. The study estimates the number of blocks used in construction was between 2-2.8 million (an average of 2.4 million), but settles on a much reduced finished total of 2 million subtracting the estimated area of the hollow spaces of the chambers and galleries. Their calculations suggest the workforce could have sustained a rate of 180 blocks per hour (3 blocks every 60 seconds)with Ten man-days for putting each individual block in place. They derived these estimates from contruction projects in the third world that did not used modern machinery.

Regardless of how many workers were required for construction, to use the following equation: 2,400,000 (total stones used in construction) ÷ 20 years (estimated time of completion) ÷ 365 days in a year ÷ 10 work hours in a day ÷ 60 minutes in one hour, the resulting answer is 0.55 stones/minute. What this means is that no matter how many workers were used or in what configuration, to complete the construction of the Great Pyramid within this time frame 1.1 blocks would have to be put in place every 2 minutes, ten hours a day, 365 days a year for twenty years. To use the same equation, but instead assuming the time of completion to be one hundred years instead of twenty, it would require 1.1 blocks to be set every ten minutes, ten hours a day, 365 days a year.

These equations, however, do not include the time and labor required to design, plan, survey, and level the 13 acre site which the Great Pyramid sits on. Nor does it include construction time for the two other main pyramids on the site, the Sphinx, the temples (which feature stones weighing upwards of 200 tonnes), networks of causeways, several square miles of paving stones (which originally covered the entire Giza plateau), the leveling of the entire Giza plateau, the 35 boat pits carved out of solid bedrock (some of which are nearly 150ft long and 30ft deep), or several other highly laborious features.

When considering the time it would have taken to build the Great Pyramid alone, it is worth noting that the construction of the entire Giza plateau is believed to have been accomplished by three pharaohs in less than a hundred years starting with Khufu who reigned from 2606-2583 BC and ending with Menkaure 2548-2530 BC (76 years). To apply the Great Pyramid labor formula to the entire Giza plateau (which only provides for the physical act of dropping the stones in place) would require stones, even the 80-200 tonne variety some of which were quarried over 500 miles away in Aswan, to be placed ten hours a day, 365 days a year for approximately 76 years - not every few minutes, but every few seconds. This feat becomes even more impessive given beginning with king Snefru who ruled from 2630-2606 BC (leaving a span of 100 years between the beginning of his reign and the end of Menkaure's in 2530 BC), three other massive pyramids were built: the Step Pyramid of Saqqara (believed to be the first egyptian pyramid), the Bent Pyramid, and the Red Pyramid of Dashur.

Herodotus speculated that the stone blocks used in the Great Pyramid's construction were maneuvered into place by raising them up a succession of short wooden scaffolds. Another possibility proposed by the ancient scholar Diodorus Siculus was that the giant blocks were dragged along a system of ramps to the necessary height. More recently, Mark Lehner speculated that a spiralling ramp, beginning in the stone quarry to the southeast and continuing around the exterior of the pyramid, may have been used. In Lehner's model, the stone blocks may have been drawn on sleds lubricated by water. Another source claims milk was a lubricant.

The most precisely cut stone blocks were reserved for the outside. Once in place their corners were smoothed to give an almost shiny outer appearance of the pyramid. For the inner core, the blocks were cut with less precisions, since there are gaps big enough to introduce an arm. This gaps were filled with rubble, mixed with gypsum. Recent studies by Gilles Dormion and Jean Patrice Goidin suggest the existence of cavities filled with sand, that could amount to 10 to 15% of the volume of the pyramid. This could reduce the amount of work required of the contruction.

The idea of using rollers to move stone blocks was made popular in Hollywood movies, but as of today, whether it be ramp, roller, or otherwise, there are few historical records to demonstrate how ground transportation was done.

If a ramp were used to push the top-most blocks of the pyramid into place, the incline would contain more material than the pyramid itself and this material would have had to be removed after construction was completed. Excavation on the area South of the Great Pyramid by revealed evidence of the remains of the ramp of the Great Pyramid, this part of the ramp consisted of two walls built of stone rubble and mixed with Tafla. The area in between was filled with sand and gypsum forming the bulk of the ramp. They were discovered during the work of relocating the Sound and Light Show cables at Giza (Hawass, The Pyramids of Ancient Egypt).

According to the theory of materials scientist Joseph Davidovits, the blocks that form the pyramid are not strictly carved stone, but mostly a form of limestone concrete (not moved, but) 'cast', as with modern cement blocks, except -- because of the blocks huge 2.5-15+ tons size -- each in situ.

It has also been suggested that Egyptians might have moved the stones with wind power, relying on kites and pulleys rather than huge numbers of slaves. On June 23, 2001, Caltech aeronautics professor Mory Gharib and a small team of undergraduates raised a 3000kg, 3m-tall obelisk into vertical position in 22mph winds in a California desert in under 25 seconds, using a 10m kite connected to a pulley system and support frame, to demonstrate that wind power can be harnessed to create large lifting forces. The originator of this idea, business consultant Maureen Clemmons, recalled seeing a building frieze now displayed in a Cairo museum, showing a wing pattern in bas relief that did not resemble any living bird, directly below which were several men standing near vertical objects that could be ropes. However, though the engineering may have been feasible, Egyptian experts point out there is no evidence that ancient Egyptians used either kites or pulleys as we know them today.

Further reading

  • Alternative Theories
Smyth, Piazzi, "Great Pyramid: Its Secrets & Mysteries Revealed". Gramercy; 4th Rep edition. October 23 1994. ISBN 0-517-26403-x
Hancock, Graham, "Fingerprints of the Gods". 3 Rivers Press; 1995. ISBN 0-517-88729-0
Verner, Miroslav, "The Pyramids - Their Archaeology and History", Atlantic Books, 2001, ISBN 1-84354-171-8

See also

Wikimedia Commons has media related to Giza.

Archeology

Exploration

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