TopTenz has posted an interesting list about ten technologies and techniques that we have lost knowledge of over the years, from Damascus steel to Roman cement.

2. Roman Cement

Modern concrete was developed in the 1700s, and today the simple mixture of cement, water, sand, and rocks is the most widely used building material in the world. But the recipe developed in the 18th century wasn’t the first time concrete was invented. In fact, concrete was widely used throughout antiquity by the Persians, Egyptians, Assyrians, and Romans. The Romans in particular made extensive use of concrete, and they were responsible for first perfecting the recipe by mixing burnt lime with crushed rocks and water. Their mastery of its use allowed them to build many of their most famous structures, among them the Pantheon, the Colosseum, the aqueducts, and the Roman Baths.

How was it Lost?

Like so many technologies of the Greeks and Romans, the recipe for concrete was lost during the descent into the Dark Ages, but just why remains a mystery. The most popular theory is that the recipe was something of a trade secret among stonemasons, and that the method for making cement and concrete died along with those who knew it. Perhaps even more interesting than the disappearance of Roman cement are the particular qualities that separate it from more modern Portland cement, which is the most common type of cement used today. Structures built with Roman cement, like the Colosseum, have managed to weather thousands of years of punishment from the elements and remain standing, but buildings constructed with Portland cement have been known to wear down much faster. This has been theorized to be the result of different chemicals that the Romans added to their cement, among them milk and even blood. These were said to create air bubbles within the concrete that helped the material to expand and contract in the heat and cold without damaging itself.

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A website has been set up by the Getty Conversation Institute in Los Angeles that allows archaeologists to gain access to decades worth of records about Jordanian sites. [Thanks @john_larkin]

The system is scheduled to open in September, but only to authorized users. Many archaeologists say they hope it will eventually become open to a much broader group of scholars and conservators around the world to view and add to, or comment upon, the information in the database.

“It’s a kind of openness that is still a very new concept in parts of the Middle East,” Mr. Whalen said.

Ziad al-Saad, the recently named director general of the Jordanian Department of Antiquities, said in a telephone interview from Amman that the country — where security and access to official information are touchy topics — was actively considering making the system freely accessible. “We want to be able to share what we have here with everyone,” he said.

He added that he considered the system an important step forward in how antiquities-rich countries like his will safeguard their treasures. “Tourism is a prime sector of our economy, and our archaeological sites are key to that,” he said. “We like to call Jordan an open museum. You find antiquities wherever you go here.”

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Ground-penetrating radar has been used to uncover a slave village on the Monocacy National Battlefield’s Best Farm.

Through other advanced remote sensing surveys, as well as labor-intensive shovel work completed since June, the excavation team had identified four chimney foundations, and what appears to be the outline of gardens or animal pens surrounding the village, Beasley said.

In a matter of hours, the surface penetrating radar pointed the way to two more, while researchers used an old-fashioned shovel test to prove the case. Both Beasley and Potter said more dwellings may exist, buried beneath the surface.

Knowing the size of the dwellings as well as cataloging and analyzing the artifacts in and around them will help the archaeologists determine how many enslaved people lived there and what their daily lives were like.

“That’s why we’re excited about this, in spite of the adversity, they made lives for themselves,” he said.

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Laser scanners are being employed on Orkney to 3D-scan some of the islands historical landmarks.

The Heart of Neolithic Orkney is made up of the tomb of Maeshowe, the Stones of Stenness, the Barnhouse Stone, the Watch Stone, the Ring of Brodgar and Skara Brae.

The recording process will involve a laser being fired millions of times a second at each of the monuments.

The end result will be a precise record of the sites, accurate down to just millimetres.

The data will be used to assess the physical condition of the structures and provide a foundation for future conservation, site management and aid archaeological understanding.

Project leader Dr Lyn Wilson said: “Though we have already scanned New Lanark, the scale and nature of the monuments will be an entirely different challenge.

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Remote sensing imagery has led to the discovery of two megalith burial sites in India which date back 3,500 years.

Spread in an area of about 6-7 km, the megaliths can be of much historical importance and have potential of being converted into a heritage site. The megaliths were located using “quick bird” remote sensing satellite launched in 2007. MRSAC directorVinod Bothale tells that the satellite has a resolution of 60 cm and hence gives good imageries. The megaliths of Junapani like all burial sites in Nagpur and adjoining districts of Gadchiroli, Chandrapur and Bhandara districts in Vidarbha are made of basalt rocks. Basalt being black the megaliths appears as small black rings on the satellite image. The Junapani burial site has about 100-125 megaliths. “This is one of the most unique uses of remote sensing imagery,” Bothale said.

Deotale says since this is one of the lesser known but big burial site it has potential of being converted into a tourist spot. Since now it lies in Gorewada project, the forest and archaeological departments could preserve the place as a heritage site. She however admits that she is not sure whether the forest department is aware of the site and its importance. Unlike other known burial sites this place has no excavation history.

The other site located by her at Mahurjari has 7 burial sites with circular formations have earlier been excavated by Nagpur University’s archaeology department. It found copper vessels, pottery and human skeleton.

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