By Ken Brooks (UK)
Local stone was an essential element in the development of early civilisations, as its availability and quality determined the building styles that they created. The effective working and use of stone as a building material was a skill acquired by man at an early stage of history in many different regions of the world. Today, we can identify their methods of working stone by studying the buildings, quarries and the tools that have survived them.
For thousands of years, the River Nile has carved its way through areas of sandstone, granite and limestone on its 750-mile journey through Egypt to the Mediterranean. From very early times, and even to the present day, the Egyptians have built their homes with bricks made from mud – an abundant raw material along the banks of the River Nile. It was around 5,000 years ago, as organised religion became established, that they began to use locally available stone to construct temples and pyramids. Between 2590BC and 2500BC, the ancient Egyptians built three huge pyramids on the Giza plateau (near present-day Cairo).
The bedrock in this area is a nummulitic limestone dating from the Eocene period, 34 to 55mya. It is an interesting thought that some of the largest man-made structures on earth were constructed from the fossil remains of tiny organisms (foraminifera). Work on a pyramid began with the extraction of limestone blocks at a nearby quarry. The only tools the Egyptians had were hammers and chisels made from stone (chert/flint or dolorite). However, with these primitive tools, the Egyptian masons managed to cut and shape great blocks of stone. Even when metals (copper, bronze and later iron) became available for this work, chert was still a popular low-cost alternative. They also used the adze, bow-drill and the saw, and used sand (quartz) as a cutting abrasive.
Each block of stone was cut and shaped to fit into the overall design of the pyramid or temple and then transported on rollers or ramps to the construction site. The pyramids were originally covered with a casing of white limestone that was cut from quarries at Tura and then transported on barges along the Nile to Giza. Unfortunately, in medieval times, most of the casing was removed for buildings in nearby Cairo. Further south, the Aswan area is well known for its beautiful pink feldspar granite, which was used mainly for statues and obelisks. Quarry workers hammered stone wedges into slots in the granite, made with chisels, until a block of stone was split from the bedrock.
From Predynastic times, much of the shaping of building blocks was done with ‘hammer stones’ known as ‘pounders’ and ‘mauls’. These were primarily of dolerite (a medium-grained intrusive igneous rock of basaltic composition), although siliceous sandstone, anorthosite gneiss and fine-grained granite were also occasionally used as hammer stones. With a number of masons working in shifts on different faces, it would probably have taken months, rather than years, to produce a roughly shaped obelisk. Igneous rocks were also employed as grinding stones for smoothing rough, carved stone surfaces on statues and obelisks. The polishing of these surfaces was probably done with ordinary, quartz-rich sand – of which there is certainly no shortage in Egypt. When ground with water, the sand becomes an abrasive paste.
The pharaoh, Ramesses II, was one of the most prolific builders in ancient Egypt. As a master of propaganda, he carried out vast building projects in his quest for immortality. Perhaps the most impressive of all his achievements is the huge temple that was carved from a cliff of red Nubian Sandstone at Abu Simbel in Upper Egypt. With four monolithic statues of him, each over 60 feet in height, he elevated himself to the status of a god on earth. From the late Middle Kingdom onward, sandstone was used for all temples within the sandstone region as well as many of those in the southern part of the limestone region. These included the temples at Denderah, Abydos and Edfu. As no mortar was used, the huge stone blocks were often held in place with ‘butterfly’ ties made from wood or copper.
Millions of years ago, tectonic forces converted local limestones into a metamorphic rock. This became the Greeks’ favourite building material – marble. The Acropolis is a huge outcrop of marble that dominates the centre of Athens. On top of this is the Parthenon – a beautiful temple that was built by Pericles between 447 and 438BC to celebrate the Greeks’ great victory over the Persians at Salamis. In fact, it was the first temple to be constructed entirely of marble (including the roof tiles), with 180,000 tons of Pentelic marble from quarries at nearby Pentelicon. The translucent pure white statues were carved from Parian marble, quarried on Paros, a Cycladic island in the Aegean Sea. Emery (corundum), which was used for polishing and cutting the marble, was mined in Naxos, another Cycladic island.
No mortar or cement was used. Blocks of marble were cut with great precision using metal tools and held in place with iron clamps. These were coated with lead to prevent corrosion (a detail overlooked during early 20th century restoration that caused even more damage when the clamps rusted).
The Parthenon is generally regarded as one of the finest examples of ancient Greek architecture, while its sculptures are considered to be the very best that Greek artists have produced.
The rocks found in Central America were also created as a result of geological events that occurred many millions of years ago. At the end of the Cretaceous period, 65 million years ago, a huge asteroid exploded in the north of what is now the Yucatan Peninsula of Mexico. The impact left a vast crater that filled with a shallow sea and sediments that eventually lithified into a creamy-white limestone. Much later, the Maya people built their pyramids and ceremonial centres from this local stone at Chichen Itza, Uxmal, Palenque and at other sites.
Natural wells (cenotes) were created when underground streams and rivers carved out caverns in the limestone, which eventually collapsed. In the dry season, these wells provided a vital supply of water for Maya settlements. They were also the home of the rain god, Chac, and during long periods of drought, human victims were sacrificed to him in the sacred well at Chichen Itza.
For millions of years, a plateau of lava, which poured from active volcanoes, has covered much of the Valley of Mexico. Even today, the most famous Mexican volcano, Popocatepetl, is still active. To the north of Mexico City, between 200BC and 100AD, the Toltecs established a huge city on the dusty volcanic plain. Temples and pyramids were built from solidified lava – a porous reddish-brown rock that is surprisingly strong and resistant to erosion. The whole complex was constructed on a rectangular grid plan, with the spectacular ‘Pyramid of the Sun’ at its centre. As the Toltecs left no written records, the city was later called Teotihuacan (‘City of the Gods’) by the Aztecs.
In Peru, the Pacific ‘Nazca’ plate is being subducted under the South American plate. Over millions of years, this tectonic process has created the Andes through volcanic activity and uplift above and along the subduction zone. Around 1200AD, the Incas built their capital city, Cuzco, high in the Peruvian Andes. It was here, surrounded by igneous rocks, that they became true masters in the use of stone. They built walls of interlocking blocks without mortar that have successfully withstood earthquakes for centuries. Large stones were shaped and fitted together so precisely that a knife blade cannot be pushed between them. The Incas not only regarded stone as a valuable building material, but also as a god whom they worshipped for its strength and permanency.
At a quarry, the masons hammered wedges into rows of chiselled slots in the rock until it split into a workable slab. This would then be carved into a rectangular shape by pounding with hammer stones made from hard cobbles of igneous rock, such as dolerite. Some of these slabs can weigh between 40 and 60 tonnes. One of the largest monolithic blocks ever worked by the Incas is 12 feet high, seven feet across and weighs over 100 tonnes. It may be seen at Sacsayhuaman, an impressive temple/fortress overlooking Cuzco.
How were the Incas able to transport huge blocks of stone without the use of draught animals or the wheel? In the absence of any written records, there have been many theories. However, the remains of cobbled roads leading to temple sites may provide an important clue. Experiments have shown that large blocks of stone could be pulled along on the cobbles by a fairly small group of workers. Even rivers might not be a problem, as stones could be dragged across on natural cobbles in shallow parts of the riverbed.
Tectonic uplift has formed mountains out of what were once deeply buried igneous rocks. It was here in the Andes that the Incas built their granite city in the clouds, perhaps as a ceremonial centre for religious rituals. This was Machu Picchu, the famous ‘lost city’ that was discovered by Hiram Bingham in 1911.
The stone working techniques employed by ancient masons illustrate their awareness of the properties of stone and geological features such as jointing and bedding. For these reasons I believe that we should recognise them as among the first true geologists.