The Geology of Egypt

The Geology of Egypt (AUC Press)

There are few sights as spectacular as sunrise in the White Desert of Egypt. The early light catches the wind-carved chalk formations and begins to play tricks on the mind. Indeed, some of the shapes are so reminiscent of figures from ancient Egyptian mythology, such as the sphinx, that it lends credence to the theory that these shapes left an indelible print on those nomadic peoples who passed through the emerging Western Desert on their way to found a brilliant civilization along the banks of the Nile.

We cannot know, of course, whether this proposed psychological influence is true, but, without a doubt, the different types of rock that can still be seen in Egypt today had an immense influence on the surviving material remains of ancient Egypt. In fact, as Bonnie Sampsell notes in The Geology of Egypt: A Traveler’s Handbook, this impact was far greater in Egypt than elsewhere — including the other great riverine civilizations of Mesopotamia, where building stone was much more of a rarity.

As in Mesopotamia, domestic architecture in Egypt tended to be ephemeral and constructed of mud-brick or poor stone, which crumbled and disappeared over time, but the distinctive monumental architectural style of ancient Egypt, and even the kingdom’s distinct borders, are largely a product of its underlying solid geology.

While very ancient rock strata are exposed in a few places within Egypt, including the first Nile cataract at Aswan, almost everywhere this very hard ‘basement complex’ is overlain by softer sandstone that, in turn, is covered by limestone of various types, which could be utilized for building (while the harder rocks, like granite and basalt, could be used for statues, sarcophagi and smaller objects).

In this manner, while ancient Egyptian civilization was undoubtedly ‘the gift of the Nile’ in that it grew up in an environment of otherwise extreme aridity, its most remarkable monuments were unquestionably a gift of the sea. For both the sandstone that characterizes the monuments of Upper Egypt and the limestone that characterizes those of Lower Egypt were created when the land was repeatedly inundated by an immense body of water — the Tethys Sea — of which the Mediterranean Sea of today is but a small remnant.

Time and time again, over millions of years, the Tethys Sea swept over what was to become Egypt creating deposits that became sandstone and limestone. As the Tethys Sea retreated northwards, more layers of limestone were formed with each inundation, leading to particularly thick deposits in the north of modern Egypt.

This process of deposition left stone, which naturally split horizontally, and which tended also to weather along vertical channels to form rough blocks — a gift, which was swiftly accepted by ancient Egyptian architects and masons using the basic hand tools available to them.

Similarly, while the location of settlements in ancient Egypt was always determined primarily by proximity to the Nile, the proximity of building materials in substantial quantities, or to easy routes into the desert where minerals and other rarer types of stones in smaller quantities could be mined or quarried or traded, was also important.

Even that most intractable of rocks, granite — formed deep in the earth from molten magma — tended to weather into conveniently sized boulders in Egypt as it approached the surface as a result of the earth’s movements, though this cannot account for all the estimated 45,000 cubic meters of granite which were shipped from Aswan to Memphis in the Old Kingdom, or for the vast amount of granite that was used later in ancient Egyptian history. Much of this must have been painstakingly chipped out using pounders made of dolerite — a hard volcanic rock similar to basalt — as we can see from the trenches surrounding the ‘unfinished obelisk’ at Aswan.

And so, indeed, to ancient Memphis and its associated pyramids — for many the most characteristic early buildings of ancient Egyptian civilization — from Dahshur in the south, via Saqqara, Abu Sir and Giza to Abu Rawash in the north. While much has been made of the transportation along the Nile of granite and fine outer stones, in each case what mattered most to architects and builders was the presence of sufficient easily quarried limestone blocks that could form the core building materials. Sometimes the layers of limestone were thin, as at Saqqara, and the blocks were small, and sometimes the layers were thick, as at Giza, and the blocks that could be quarried nearby were of massive proportions. Each time a new pyramid was to be built, the site shifted to be in close proximity to a viable quarry.

A visit to any of the surviving monumental buildings of ancient Egypt or a day spent in the Egyptian Museum easily demonstrates the mastery with which ancient masons learned to handle stone and provides proof, if further proof were needed, that ancient Egypt truly rocked!

This is a modified version of an illustrated article which first appeared in Egypt Today: http://egypttoday.com/blog/2016/05/12/the-stones-of-ancient-egypt/

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