Pyramids riddle solved? Lost branch of Nile may have been key to construction

Experts believe ancient Egyptians used a nearby waterway to transport millions of 2.3-tonne stone blocks

The Giza Pyramids. Research suggests the area was not always desert. AFP

Researchers have uncovered evidence that bolsters theories that ancient Egyptians used a lost arm of the Nile to transport the huge limestone and granite blocks used to build the Great Pyramids.

The largest pyramid field in Egypt, which includes the Giza complex, is today far from the Nile in a narrow desert strip.

But experts have long suspected that millions of blocks, which each weigh about 2.3 tonnes, were moved using the river, with a branch of the Nile once flowing nearby.

A team of researchers used satellite imagery to find the possible location of a former branch running along the foothills of the Western Desert plateau, close to the pyramid fields.

By studying geophysical surveys, they discovered river sediments and lost channels beneath the modern land surface, indicating the presence of a major former branch, which they propose naming Ahramat, which means "pyramids" in Arabic.

Many of the pyramids had causeways, which experts believe ended at the banks of the Ahramat branch, suggesting the Nile was used for moving construction materials.

They say this would explain why the pyramid fields are concentrated along the desert strip near the ancient Egyptian capital of Memphis, because they would have been easily accessible via the river branch at the time when they were built.

“The enormity of this branch and its proximity to the pyramid complexes, in addition to the fact that the pyramids’ causeways terminate at its riverbank, all imply that this branch was active and operational during the construction phase of these pyramids,” wrote the authors, based in the US, Australia and Egypt.

“This waterway would have connected important locations in ancient Egypt, including cities and towns, and therefore played an important role in the cultural landscape of the region.”

Egypt's pyramids of Giza - in pictures

The researchers suspect a build-up of windblown sand, linked to a major drought which began about 4,200 years ago, may have caused the branch’s migration east before it eventually silted up.

In 2013, papyrus fragments were discovered near the Red Sea, which recounted how men moved the limestone blocks up the Nile river to Giza, giving researchers the first evidence to prove their theory about how the pyramids were built.

Previous studies have also uncovered evidence of a lost branch of the Nile.

During the African Humid Period, which occurred between 14,800 and 5,500 years ago, northern Africa was much wetter than it is today.

The Giza area, which was flooded for centuries, gradually dried out over a period of thousands of years.

Scientists think ancient Egyptian engineers built a system of canals and basins stretching from a port at the foot of the Giza plateau to take advantage of the Nile’s annual floods and build the pyramids.

It is believed that larger vessels could only use the waterways during the annual flood season, which takes place from August to October, when water levels in the Nile channel rose by about seven metres.