The fascination of large stones

There is a perennial interest in the megaliths (large stones) used in ancient construction. Sometimes the interest is driven by conspiracy theories. But what are the facts?

Stonehenge (click to zoom, photo by Adrian Pingstone – link)

Around 2580 BC, construction of the Great Pyramid of Giza began, using stones of up to 50 metric tonnes in weight. At about the same time, stones of similar weight were being erected at Stonehenge. Somewhat later, in 1350 BC, the Colossi of Memnon (650-tonne statues) were erected in Egypt

The Western Stone, Jerusalem (photo by David Shankbone – link)

The Western Stone is a large stone block at the base of the Western Wall in Jerusalem. It formed part of the Jewish Temple built by Herod the Great. Herodian architecture was characterised by large closely-fitting chiselled stone blocks, and the Western Stone is one of the largest, weighing about 500 metric tonnes.

Stone of the Pregnant Woman, Baalbek

At about the same time, construction of the Temple of Jupiter began in what is now Baalbek, Lebanon. Stones of up to 800 metric tonnes were used in the foundations. The quarry was 900 metres away, and still contains the 1,000-tonne Stone of the Pregnant Woman, which was not completely separated from the surrounding rock, and was never used. This stone was quarried at an angle, in order to allow it to be easily dropped onto rollers or a sledge.

Later centuries saw the Moai statues of Easter Island and the walls of Cuzco, although these involved weights far less than those of Roman construction.

The Russian Thunder Stone, during transport and in final form (photo on right by Andrew Shiva – link)

The Thunder Stone was a large granite boulder (of about 1,500 metric tonnes) discovered in Russia and transported to Saint Petersburg to be used (after some shaping) as the base of a statue of Peter the Great. Transport took about nine months, being completed in 1770. On land, a sledge was used, pulled by 400 men and rolling over bronze spheres. A special barge was used at sea. This boulder represents the pinnacle of megalith construction. For comparison, its weight was a little over the maximum capacity of a modern mobile crane, such as the Liebherr LTM 11200-9.1.

Construction of the Mussolini Obelisk, Rome

One of the most recent examples is the Mussolini Obelisk in Rome, constructed in 1929 during the fascist regime of Benito Mussolini. Carved from Carrara marble, it weighed around 300 metric tonnes, and was transported on land using a sledge running over planks lubricated with soap. The sledge was pulled by 36 pairs of oxen in Tuscany, and by a tractor in Rome. As with the Thunder Stone, a barge was used at sea. This was perhaps the last example of megalith construction using primarily ancient techniques. Since then, there have been more impressive examples of construction, but using smaller components, newer techniques, and more modern materials. The days of using large stones are over!

The chart below summarises the megaliths we have listed here.

Solar Car Racing in Egypt: Update

Time for an update on the Somabay Egyptian Solar Challenge. Scrutineering was due to have begun, but apparently all the cars are still held up in customs. Hopefully the race itself will still start on the 17th. Apparently the route will run north and south along the Red Sea shore for four days, and finish at the Pyramids of Giza on the fifth day.

With luck, we will get some news from mostdece during the race, because the official Twitter and Facebook feeds are not saying much. The following three teams have active news feeds:

DE  Bochum University of Applied Sciences 

Bochum are putting up very detailed daily blog posts (in German) at Their local partners from Cairo University are active on Facebook (and, amazingly, auto-translate works well).

FR  Eco Solar Breizh 

This Breton team is active on Facebook and Twitter (click on the icons above).

NL  Nuon Solar Team 

Nuon is extremely active on Twitter, posting news, pictures, and short videos.

Update 1: apparently the race organisers have no permit to conduct the race as planned. The race will therefore be reduced to a 2-day event, running laps around the Somabay resort complex.

Update 2: Nuon has a report on the event here.

Solar Car Racing in Egypt

The solar car teams below have said that they intend to race at the Somabay Egyptian Solar Challenge this March. Details of the race are still rather thin on the ground – no route has yet been announced, and there is no official list of teams. There are, however, Twitter and Facebook feeds for the race. Those thinking about participating should probably note the travel advice from Australian, US, Dutch, and French authorities.

DE  Bochum University of Applied Sciences 

This team came 3rd in the Cruiser class at WSC 2015. They also entered three cars in the 2016 ESC, coming 3rd, 4th, and 5th.

TR  Dokuz Eylül University / Solaris 

This team came 25th in the Challenger class at WSC 2015. They raced in the 2016 ESC, coming 9th.

FR  Eco Solar Breizh 

This is a French (or rather, Breton) team, started in 2008. They raced at ESC in 2014.

NL  Nuon Solar Team 

This team came 1st in the Challenger class at WSC 2015. They also raced in the 2016 Sasol Solar Challenge in South Africa, coming 1st.

JP  Osaka Sangyo University (OSU)

EG  Solar Electric Vehicle – Cairo University Team 

This is a local Egyptian team. They are partnering with Bochum, it seems. They are also planning to race at WSC 2017.

EG  Zewail City Solar Car Team 

This is a local Egyptian team. They are partnering with OSU, it seems. They are also planning to race at WSC 2017.

This post last updated 17:04 on 01 March 2017 AEDT

Carbon dating: Science in the service of History

In 1949, Willard Libby proposed carbon dating, a method for dating carbon-containing objects (like wood, leather, or cloth) that exploits the radioactive decay of carbon-14. The diagram above [redrawn from J. R. Arnold & W. F. Libby, “Age Determinations by Radiocarbon Content: Checks with Samples of Known Age,” Science 110 (2869), 678–680, 23 Dec 1949] shows the decay curve for carbon-14, together with some comparison samples Libby used (including wood dated by tree rings and items from the tomb of Pharaoh Zoser, for whom the first of the pyramids was built). It’s a very good fit! Later tests of carbon-dating have used dendrochronology back to about 10,000 BC.

The carbon in plants contains about one part per trillion of carbon-14, which the plants absorb from the atmosphere. The same amount of carbon-14 is present in animals, which get their carbon by eating plants or other animals. All living things therefore contain about one part per trillion of carbon-14. In dead plants or animals, however, the carbon-14 decays with a half-life of 5,730 years. For practical dating purposes, measurements of carbon-14 are adjusted to match the tree-ring data, so as to compensate for small changes in the amount of atmospheric carbon-14 over time. Such calibrated dates are reported as “Before Present” (BP), where “Present” means 1 January 1950.

One of the most famous examples of carbon-dating has been the Shroud of Turin, purported to be the burial shroud of Jesus Christ, and shown below in a negative image from 1898. The Shroud has been carbon-dated to between 1260 and 1390 AD, which is consistent with its denunciation as a forgery by the Bishop of Troyes in 1389, shortly after it first appeared on the historical scene. For the dating story, see P. E. Damon et al., “Radiocarbon Dating of the Shroud of Turin,” Nature 337 (6208), 611–615, 16 Feb 1989.