forensic archaeology

notre-dame-cathedral-first-to-use-iron-reinforcements-in-12th-century

Notre Dame cathedral first to use iron reinforcements in 12th century

12 days of Christmas, Archaeology, architecture, forensic archaeology, medieval architecture, notre dame, Science / /

On the twelfth day of Christmas —

Devastating 2019 fire gave scholars access to previously hidden parts of the cathedral.

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View of the chevet of Notre-Dame de Paris under restoration.

Enlarge / The Notre-Dame de Paris has been under restoration since a devastating fire destroyed the main spire and roof in April 2019.

There’s rarely time to write about every cool science-y story that comes our way. So this year, we’re once again running a special Twelve Days of Christmas series of posts, highlighting one science story that fell through the cracks in 2023, each day from December 25 through January 5. Today: The Notre Dame cathedral in Paris has been undergoing extensive renovation in the wake of a devastating 2019 fire. Previously hidden portions of its structure have revealed the use of iron reinforcements in the earliest phases of the cathedral’s construction, making it the earliest known building of its type to do so.

On April 15, 2019, the world watched in collective horror as the famed Notre Dame cathedral in Paris was engulfed in flames. The magnificent cathedral’s roof and its support structure of 800-year-old oak timbers were destroyed when the main spire—750 tons of oak lined with lead—collapsed in flames, landing on the wooden roof. French President Emmanuel Macron vowed to rebuild the cathedral, and that work has continued steadily in the ensuing years; the current planned re-opening will occur on December 8, 2024.

If there is a silver lining to the destruction, it’s that the damage has revealed parts of the cathedral’s structure that were previously inaccessible, telling archaeologists and conservationists more about the materials originally used to construct Notre Dame in the mid-12th century. According to a March 2023 paper published in the journal PLoS ONE, the original builders used iron reinforcements during the initial phases, making Notre Dame the earliest building of its type to do so.

“The fire has shed light on certain uses of iron, such as the staples on the top of the upper walls which were totally hidden by the framework,” co-author Maxime L’Héritier of Université Paris told Gizmodo. “We could not have seen them without the blaze or a huge restoration. We believed that [the] great building yards of the 13th century had invented these construction processes using iron armatures, but now it seems that it all occurred at Notre Dame.”

Although no original plans for Notre Dame Cathedral exist, a couple of centuries after Notre Dame’s construction, other building projects left behind documents called building accounts or fabric accounts, which include information like materials purchases and payments to masons. But in the late 12th century, written documents weren’t yet widely used. In the early 1800s, the cathedral was crumbling, and architects Eugène Viollet-le-Duc and Jean-Baptiste-Antoine Lassus received a royal contract to restore the medieval structure. Working with relatively simple tools, Viollet-le-Duc left behind detailed, accurate drawings of the original architecture and his own restoration work.

Two hundred years later, art historian Stephen Murray and the late architectural historian Andrew Tallon of Vassar College carried laser scanners through the entire cathedral, including the space above the vault and several out-of-the-way spiral staircases, passages, and other hidden spaces. As for the cathedral’s much-praised acoustics, a group of French acousticians made detailed measurements of Notre Dame’s “soundscape” a few years before the fire. All of that data has been instrumental in helping architects and conservationists reconstruct the cathedral.

The 2019 fire exposed iron staples in the top walls, inside a column in the nave, and in the tribunes of the choir.

Enlarge / The 2019 fire exposed iron staples in the top walls, inside a column in the nave, and in the tribunes of the choir.

M. L’Heritier et al. 2023

Other medieval French cathedrals built after Notre Dame, such as in Chartres, Bourges, or Reims, all used iron armatures, tie-rods, and chains. But until now, it hasn’t been clear to what extent the original builders of Notre Dame used iron in its construction. Harnessing and scaffolding gave researchers access to the upper parts of the cathedral, although some parts remained inaccessible. Still, L’Héritier et al. found extensive use of iron staples at different levels, with the lowest being two rows of staples in the floors of the second-level tribunes above the arches, as well as in the nave and choir.

Per the authors, some iron reinforcements clearly dated back to reconstruction efforts during the 19th century, most notably iron chains and tie rods in the top walls of the choir and above its upper vaults. The real question was just how old the other iron staples might be. The team mapped and measured all those that were accessible, totaling roughly 170 staples for the upper walls and 100 for the tribunes. They also took samples for the metallographic analysis from iron staples that were already broken or damaged by the fire. The team used a new method for characterizing metal, combined with radiocarbon dating, to determine the age and possible provenance of those samples.

Broken iron staple in the tribunes.

Enlarge / Broken iron staple in the tribunes.

M. L’Heritier et al. 2023

L’Héritier et al. concluded that the iron staples in the floor of the tribunes dated back to the early 1160s, i.e., the earliest phases of construction. “So far, these series of staples are the earliest known example of iron armatures used in the initial design of a Gothic monument,” they wrote, a good 40 years before the iron reinforcements used to build the Chartres or Bourges cathedrals. The staples found at the top of the great lateral walls date to the early 13th century, indicating that the architects of that period also relied on iron reinforcements.

As for the iron itself, the metal analysis showed that the iron alloys used to make the staples were common to the Middle Ages and of similar quality to those found at Chartres, Troyes, and similar cathedrals. What makes the Notre Dame staples unusual is the presence of welding lines, indicating that several pieces of iron of different provenances were welded together to form each staple. Tracking those supply sources could shed light on the iron trade, circulation, and forging in 12th and 13th century Paris.

“Compared to other cathedrals, such as Reims, the structure of Notre Dame in Paris is light and elegant,” Jennifer Feltman of the University of Alabama, who was not involved in the research, told New Scientist. “This study confirms that use of iron made this lighter structure at Paris possible and thus the use of this material was crucial to the design of the first Gothic architect of Notre Dame.”

PLoS ONE, 2023. DOI: 10.1371/journal.pone.0280945  (About DOIs).

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How archaeologists reconstructed the burning of Jerusalem in 586 BCE

12 days of Christmas, antiquities, Archaeology, biblical archaeology, biblical texts, chemistry, forensic archaeology, Hebrew bible, Science / /

On the seventh day of Christmas —

Hebrew bible is only surviving account of siege that laid waste to Solomon’s Temple.

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How archaeologists reconstructed the burning of Jerusalem in 586 BCE

Assaf Peretz/Israel Antiquities Authority

There’s rarely time to write about every cool science-y story that comes our way. So this year, we’re once again running a special Twelve Days of Christmas series of posts, highlighting one science story that fell through the cracks in 2020, each day from December 25 through January 5. Today: Archaeologists relied on chemical clues and techniques like FTIR spectroscopy and archaeomagnetic analysis to reconstruct the burning of Jerusalem by Babylonian forces around 586 BCE.

Archaeologists have uncovered new evidence in support of Biblical accounts of the siege and burning of the city of Jerusalem by the Babylonians around 586 BCE, according to a September paper published in the Journal of Archaeological Science.

The Hebrew bible contains the only account of this momentous event, which included the destruction of Solomon’s Temple. “The Babylonian chronicles from these years were not preserved,” co-author Nitsan Shalom of Tel Aviv University in Israel told New Scientist. According to the biblical account, “There was a violent and complete destruction, the whole city was burned and it stayed completely empty, like the descriptions you see in [the Book of] Lamentations about the city deserted and in complete misery.”

Judah was a vassal kingdom of Babylon during the late 7th century BCE, under the rule of Nebuchadnezzar II. This did not sit well with Judah’s king, Jehoiakim, who revolted against the Babylonian king in 601 BCE despite being warned not to do so by the prophet Jeremiah. He stopped paying the required tribute and sided with Egypt when Nebuchadnezzar tried (and failed) to in invade that country.  Jehoiakim died and his son Jeconiah succeeded him when Nebuchadnezzar’s forces besieged Jerusalem in 597 BCE. The city was pillaged and Jeconiah surrendered and was deported to Babylon for his trouble, along with a substantial portion of Judah’s population. (The Book of Kings puts the number at 10,000.) His uncle Zedekiah became king of Judah.

Zedekiah also chafed under Babylonian rule and revolted in turn, refusing to pay the required tribute and seeking alliance with the Egyptian pharaoh Hophra. This resulted in a brutal 30-month siege by Nebuchadnezzar’s forces against Judah and its capital, Jerusalem. Eventually the Babylonians prevailed again, breaking through the city walls to conquer Jerusalem. Zedekiah was forced to watch his sons killed and was then blinded, bound, and taken to Babylon as a prisoner. This time Nebuchadnezzar was less merciful and ordered his troops to completely destroy Jerusalem and pull down the wall around 586 BCE.

There is archaeological evidence to support the account of the city being destroyed by fire, along with nearby villages and towns on the western border. Three residential structures were excavated between 1978 and 1982 and found to contain burned wooden beams dating to around 586 BCE. Archaeologists also found ash and burned wooden beams from the same time period when they excavated several structures at the Giv’ati Parking Lot archaeological site, close to the assumed location of Solomon’s Temple. Samples taken from a plaster floor showed exposure to high temperatures of at least 600 degrees Celsius

Aerial view of the excavation site in Jerusalem, at the foot of the Temple Mount

Enlarge / Aerial view of the excavation site in Jerusalem, at the foot of the Temple Mount

Assaf Peretz/Israel Antiquities Authority

However, it wasn’t possible to determine from that evidence whether the fires were intentional or accidental, or where the fire started if it was indeed intentional. For this latest research, Shalom and her colleagues focused on the two-story Building 100 at the Giv’ati Parking Lot site. They used Fourier transform infrared (FTIR) spectroscopy—which measures the absorption of infrared light to determine to what degree a sample had been heated—and archaeomagnetic analysis, which determines whether samples containing magnetic minerals were sufficiently heated to reorient those compounds to a new magnetic north.

The analysis revealed varying degrees of exposure to high-temperature fire in three rooms (designated A, B, and C) on the bottom level of Building 100, with Room C showing the most obvious evidence. This might have been a sign that Room C was the ignition point, but there was no fire path; the burning of Room C appeared to be isolated. Combined with an earlier 2020 study on segments of the second level of the building, the authors concluded that several fires were lit in the building and the fires burned strongest in the upper floors, except for that “intense local fire” in Room C on the first level.

“When a structure burns, heat rises and is concentrated below the ceiling,” the authors wrote. “The walls and roof are therefore heated to higher temperatures than the floor.” The presence of charred beams on the floors suggest this was indeed the case: most of the heat rose to the ceiling, burning the beams until they collapsed to the floors, which otherwise were subjected to radiant heat. But the extent of the debris was likely not caused just by that collapse, suggesting that the Babylonians deliberately went back in and knocked down any remaining walls.

Furthermore, “They targeted the more important, the more famous buildings in the city,” Shalom told New Scientist, rather than destroying everything indiscriminately. “2600 years later, we’re still mourning the temple.”

While they found no evidence of additional fuels that might have served as accelerants, “we may assume the fire was intentionally ignited  due to its widespread presence in all rooms and both stories of the building,” Shalom et al. concluded. “The finds within the rooms indicate there was enough flammable material (vegetal and wooden items and construction material) to make additional fuel unnecessary. The widespread presence of charred remains suggests a deliberate destruction by fire…. [T]he spread of the fire and the rapid collapse of the building indicate that the destroyers invested great efforts to completely demolish the building and take it out of use.”

DOI: Journal of Archaeological Science, 2023. 10.1016/j.jas.2023.105823  (About DOIs).

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A forensic artist has given a 500-year-old Inca “ice maiden” a face

12 days of Christmas, forensic anthropology, forensic archaeology, forensic reconstruction, inca, Science / /

On the fourth day of Christmas —

Dubbed “Juanita,” the young woman was likely killed during a sacrificial ritual.

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The final approximation of the Incan girl wearing clothing that's similar to what she wore when she died.

Enlarge / The final approximation of the Incan girl dubbed “Juanita” wearing clothing similar to what she was wearing when she died.

Dagmara Socha

There’s rarely time to write about every cool science-y story that comes our way. So this year, we’re once again running a special Twelve Days of Christmas series of posts, highlighting one science story that fell through the cracks in 2023, each day from December 25 through January 5. Today: Swedish forensic artist Oscar Nilsson combined CT scans of frozen mummified remains with skull measurements and DNA analysis to reconstruct the face of a 500-year-old Inca girl.

In 1995, archaeologists discovered the frozen, mummified remains of a young Inca girl high in the mountains of Peru, thought to have died as part of a sacrificial ritual known as Capacocha (or Ohapaq hucha). In late October, we learned how she most likely looked in life, thanks to a detailed reconstruction by Swedish forensic article Oscar Nilsson. A plaster bust of the reconstruction was unveiled at a ceremony at the Andean Sanctuaries Museum of the Catholic University of Santa Maria in Arequipa, Peru, where the girl’s remains (now called Juanita) have been on near-continuous display since her discovery.

“I thought I’d never know what her face looked like when she was alive,” archaeologist Johan Reinhardt told the BBC. Reinhardt had found the remains with Peruvian mountaineer Miguel Zárate at an altitude of 21,000 feet (6,400 meters) during an expedition to Ampato, one of the highest volcanos in the Andes. “Now 28 years later, this has become a reality thanks to Oscar Nilsson’s reconstruction.”

According to Reinhardt, Spanish chroniclers made reference to the Inca practice of making offerings to the gods: not just statues, fine textiles, and ceramics, but also occasionally human sacrifices at ceremonial shrines (huacas) built high on mountain summits. It’s thought that human sacrifices of young girls and boys were a means of appeasing the Inca gods (Apus) during periods of irregular weather patterns, particularly drought. Drought was common in the wake of a volcanic eruption.

During those periods, the ground on summits would unfreeze sufficiently for the Incas to build their sites and bury their offerings. The altitude is one reason why various Inca mummified remains have been found in remarkable states of preservation.

Earlier discoveries included the remains of an Inca boy found by looters in the 1950s, as well as the frozen body of a young man in 1964 and that of  a young boy in 1985. Then Reinhardt and Zárate made their Ampato ascent in September 1995. They were stunned to spot a mummy bundle on the ice just below the summit and realized they were looking at the frozen face of a young girl. The body was surrounded by offerings for the Inca gods, including llama bones, small carved figurines, and bits of pottery. Juanita was wrapped in a colorful burial tapestry and wearing a feathered cap and alpaca shawl, all almost perfectly preserved. Reinhardt and Zárate subsequently found two more ice mummies (a young boy and girl) the following month, and yet another female mummy in December 1997.

Reconstructing the face of the Incan

Enlarge / Reconstructing the face of the Incan “ice maiden” took nearly 400 hours.

Oscar Nilsson

It was a bit of a struggle to get Juanita’s body down from the summit because it was so heavy, the result of its flesh being so thoroughly frozen. That’s also what makes it such an exciting archaeological find. The remains of meal of vegetables were in her well-reserved stomach, although DNA analysis from her hair showed that she also ate a fair amount of animal protein. That, and the high quality of her garments, suggested she came from a noble family, possibly from the city of Cusco.

There were also traces of coca and alcohol, likely administered before Juanita’s death—a common Inca practice when sacrificing children. A CT scan of her skull revealed that Juanita had died from a a sharp blow to the head, similar to the type of injury made by a baseball bat, causing a massive hemorrhage. This, too, was a common Inca sacrificial custom.

Nilsson was able to draw upon those earlier analyses for his reconstruction, since he needed to know things like her age, gender, weight, and ethnicity. He started with the CT scan of Juanita’s skull and used the data to 3D print a plastic replica of her head. He used wooden pegs on the bust to mark out the various measurements and added clay to mold the defining details of her face, drawing on clues from her nose, eye sockets, and teeth. The DNA indicated the likely color of her skin. “In Juanita’s case, I wanted her to look both scared and proud, and with a high sense of presence at the same time,” Nilsson told Live Science. “I then cast the face in silicone [using] real human hair [that I] inserted hair by hair.”

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