Little is known about the origins of manikins--small anatomical sculptures thought to be used by doctors four centuries ago--but now advanced imaging techniques have offered a revealing glimpse inside these captivating ivory dolls. Researchers using micro-CT successfully identified the material composition and components of several ancient ivory manikins, according to a new study being presented next week at the annual meeting of the Radiological Society of North America (RSNA).
This is an ivory figurine reclining on its 'bed' with all organs placed inside [Credit: Fides R. Schwartz, RSNA]
Ivory manikins are typically thought to have been carved in Germany in the late 17th century. They are reclining human figurines, 4-8 inches long, generally female, which open to reveal removable organs and sometimes a fetus attached with a fabric "umbilical" cord. The manikins have intricately carved features, and some even have pillows beneath their heads. It is believed that they were used for the study of medical anatomy or perhaps as a teaching aid for pregnancy and childbirth. By the 18th century, they had been replaced by more realistic teaching tools, such as wax models and cadavers. The manikins then became objects of curiosity and luxury status symbols in private collections.
Duke University in Durham, N.C., holds the world's largest collection of manikins (22 out of 180 known manikins worldwide). Most of the manikins in the Duke collection were purchased in the 1930s and 1940s by Duke thoracic surgeon Josiah Trent, M.D., and his wife Mary Duke Biddle Trent, prior to the 1989 ivory trade ban. The researchers noted that after being donated to the university by Trent's granddaughters, the manikins have spent most of their time in archival storage boxes or behind display glass, as they are too fragile for regular handling.
"They are usually stored in a library vault and occasionally rotated into a special display unit in the Duke Medical Library for visitors to appreciate," said Fides R. Schwartz, M.D., research fellow in the Department of Radiology at Duke.
Non-destructive imaging with X-rays and CT has been used in the past to examine fragile artwork and ancient artifacts. Imaging of relics has been extremely beneficial to the fields of archaeology and paleopathology--the study of ancient diseases.
This is an Ivory manikin after removal of the abdominal and chest wall, ribs, and part of the uterus. Internal organs such as the lungs, intestines, as well as a fetus inside the uterus are visible [Credit: Fides R. Schwartz, RSNA]
Micro-CT is an imaging technique with greatly increased resolution, compared to standard CT. It not only allows visualization of internal features, it noninvasively provides volumetric information about an object's microstructure.
Dr. Schwartz and colleagues hoped that through micro-CT imaging they could determine the ivory type used in the Duke manikins, discover any repairs or alterations that were not visible to the naked eye, and allow a more precise estimation of their age.
"The advantage of micro-CT in the evaluation of these manikins enables us to analyze the microstructure of the material used," she said. "Specifically, it allows us to distinguish between 'true' ivory obtained from elephants or mammoths and 'imitation' ivory, such as deer antler or whale bone."
The research team scanned all 22 manikins with micro-CT and found that 20 out of the 22 manikins were composed of true ivory alone, though materials like antler might have been less expensive in that time. They discovered that one manikin was made entirely of antler bone, and one manikin contained both ivory and whale bone components.
Micro-CT initial scan data. The internal organs and fetus inside the uterus are visible, similar to a photograph [Credit: Fides R. Schwartz, RSNA]
Metallic components were found in four of the manikins, and fibers in two. Twelve manikins contained hinging mechanisms or internal repairs with ivory pins, and one manikin contained a long detachable pin disguised as a hairpiece.
The most established trade routes in the 17th and 18th centuries sourced ivory from Africa, leading the researchers to believe that since nearly all of the manikins were made from true ivory, it is likely that the ivory obtained to craft the manikins was acquired from the African region.
"This may assist in further narrowing down the most probable production period for the manikins," Dr. Schwartz said. "Once historical trade routes are more thoroughly understood, it might become clear that the German region of origin had access to elephant ivory only for a limited time during the 17th and 18th century, for example, from 1650 to 1700 A.D."
Additionally, identifying non-ivory components in the manikins may provide more accessibility to carbon dating, allowing the researchers to more accurately estimate the age of some of the manikins without damage to the fragile pieces.
The researchers also hope to acquire 3D scans to create digital renderings and enable subsequent 3D printed models.
"This is potentially valuable to scientific, historic and artistic communities, as it would allow display and further study of these objects while protecting the fragile originals," Dr. Schwartz said. "Digitizing and 3D printing them will give visitors more access and opportunity to interact with the manikins and may also allow investigators to learn more about their history."
Using drone technology, a team of UF researchers has uncovered how an ancient Florida village played a pivotal role in pre-Columbian geopolitics.
A drone equipped with Light Detection and Ranging quickly collected architectural details and topographic data about he Raleigh Island settlement with unprecedented resolution. The images revealed rings made of oyster shells surrounding 37 residences [Credit: University of Florida]
In research led by anthropology Ph.D. student Terry Barbour, the team discovered that the settlement on Raleigh Island, located on the northern Gulf coast of Florida around 900–1200 AD, operated as a major producer of beads made from seashells. The beads, used in rituals at the time, were highly prized in communities as far from the coast as the lower Midwest.
"In form, scale and purpose, the Raleigh Island settlement has no parallel in the archaeological record of the American Southeast," said Ken Sassaman, Barbour's advisor and the co-creator of the study. Sassaman is the Hyatt and Cici Brown Professor of Florida Archaeology in the Department of Anthropology.
The researchers used drones to survey the ancient settlement in a fraction of the time traditional methods would have taken. Working with UF partners at the GatorEye Unmanned Flying Laboratory, the team equipped the drone with Light Detection and Ranging (LiDAR) scanners that quickly collected architectural details and topographic data with unprecedented resolution.
The LiDAR shed light on how the settlement—a complex of at least 37 residential spaces surrounded by 4-meter-tall ridges of oyster shells—was organized to make beads in the very place where shells were found. In several of the living spaces, the researchers' excavations uncovered ample evidence of large-scale bead production.
The Raleigh Island settlement is one of the few coastal communities where such extensive craft production has been found.
"What we have here is a settlement at the source of this raw material at the time when marine shell was starting to become a heavily demanded social item," Barbour said. "The fact we have strong evidence of bead manufacture at a site with equally impressive architecture to guide us in understanding how production was organized socially makes this place really special, and as of now the only place like it we are aware of."
The U.S. ambassador to Italy has returned to Italian officials the head of a statue stolen from an archaeological site in Rome in 1968.
Credit: Carabinieri dei Beni Culturali
Ambassador Lewis Eisenberg handed over the marble head of the mythical figure Pan to Culture Minister Dario Franceschini Thursday on the 50th anniversary of a Carabinieri unit dedicated to the recovery of cultural artifacts.
Carabinieri special investigators spotted the marble head in a California auction catalog in 2016 and notified their U.S. counterparts.
U.S. attache Armando Astorga said the piece entered the United States in the mid-2000s, after spending many years in private hands in Europe.
So far, the investigation has not determined the original thief.
U.S. Homeland Security Investigations has repatriated some 12,000 items to over 35 countries since 2007.
A total of 1,783 Achaemenid-era clay tablets, which were on loan from Iran to the Oriental Institute of the University of Chicago since 1935, have been returned home.
Credit: Iranian Ministry of Cultural Heritage
The fourth batch of the Achaemenid objects, composed of 1783 clay tablets, entered the country from the Oriental Institute after 84 years, CHTN reported.
They are part of thousands of clay tablets and related fragments, which were kept at Chicago’s Field Museum of Natural History and the University of Chicago’s Oriental Institute.
Credit: Iranian Ministry of Cultural Heritage
The artifacts were recuperated with great deal of efforts made by the Ministry of Cultural Heritage, Tourism and Handicrafts and the presidential office for legal affairs, tourism minister Ali-Asghar Mounesan said.
The tablets were handed over to the National Museum of Iran, where they are supposed to be put on show as of tomorrow.
Credit: Iranian Ministry of Cultural Heritage
“These treasured documents decipher an important segment of recorded history of Achaemenids during the reign of Darius I (Darius the Great who reigned from 522 to 486 BC),” said Jebrael Nokandeh, director of the National Museum of Iran.
Last December, Mounesan announced that over 11,000 flawless [Achaemenid-era] clay tablets and a large number of fragments of their kind will be back home.
Credit: Iranian Ministry of Cultural Heritage
“Of the cited number, 1784 clay tablets have been endorsed by the U.S. Department of the Treasury in order to be shipped to Iran, in the first stage… and they are currently being packed by the Oriental Institute of the University of Chicago,” Mounesan said.
In February 2018, and following years of ups and downs, the fate of those ancient Persian artifacts, was left in the hands of a U.S. Supreme Court, which ruled in favor of Iran.
Credit: Iranian Ministry of Cultural Heritage
Archaeologists affiliated with the University of Chicago discovered the tablets in 1930s while excavating in Persepolis, the ceremonial capital of the Persian Empire. However, the institute has resumed work in collaboration with colleagues in Iran, and the return of the tablets is part of a broadening of contacts between scholars in the two countries, said Gil Stein, director of the Oriental Institute at the University of Chicago.
The tablets reveal economic, social and religious history of the Achaemenid Empire (550-330 BC) and the larger Near Eastern region in the fifth century BC.
Credit: Iranian Ministry of Cultural Heritage
Darius I (born 550 BC—died 486), king of Persia in 522–486 BC, one of the greatest rulers of the Achaemenid dynasty, who was noted for his administrative genius and for his great building projects. Darius attempted several times to conquer Greece; his fleet was destroyed by a storm in 492, and the Athenians defeated his army at Marathon in 490.
The Achaemenid [Persian] Empire was the largest and most durable empire of its time. The empire stretched from Ethiopia, through Egypt, to Greece, to Anatolia (modern Turkey), Central Asia and to India.
The Institute for the Study of the Ancient World presents A Wonder to Behold: Craftsmanship and the Creation of Babylon’s Ishtar Gate, opening new avenues for understanding one of the most spectacular achievements of the ancient world. On view from November 6, 2019, through May 24, 2020, the exhibition features 180 objects that bring to life the synthesis of masterful craftsmanship and ancient beliefs that transformed clay, minerals, and organic materials—seen as magically potent substances—into this powerful monument.
Reconstructed panel of bricks with a striding lion Neo-Babylonian Period; Processional Way, El-Kasr Mound, Babylon, Iraq [Credit: The Metropolitan Museum of Art]
A Wonder to Behold demonstrates how the master craftspeople who designed and built the Ishtar Gate and its affiliated Processional Way were not simply skilled technicians—though they were certainly that— but also artists, historians, and ritual practitioners known as “experts” (ummanu). They were believed capable of creating artworks that manifested divine powers on Earth, and the Ishtar Gate, offering entry into the imperial city of Babylon, was designed to be one such magically activated monument.
A Wonder to Behold has been organized by ISAW and co-curated by its Associate Director of Exhibitions and Gallery Curator, Clare Fitzgerald, PhD, with guest curators Anastasia Amrhein, an art historian specializing in the ancient Middle East (University of Pennsylvania), and Elizabeth Knott, PhD, a historian specializing in the textual and visual remains of the ancient Middle East (NYU).
Dr. Fitzgerald states, “ISAW is thrilled to present A Wonder to Behold, which follows the transformation of commonplace, if sacred, materials as they journey from the brickyards to one of the greatest monuments of the ancient world, a divinely protected and ritualized entryway to the inner city of Babylon. In so doing, the exhibition opens a window onto both ancient beliefs and superb artistic skills, and expands our understanding of the critical role of craftspeople in the ancient Middle East. ISAW is grateful to Anastasia Amrhein and Elizabeth Knott, who have brought their deep knowledge to this exhibition.”
Built over the course of King Nebuchadnezzar II’s reign (r. 604–562 BCE), the Ishtar Gate (named in honor of the Mesopotamian goddess Ishtar) was at the epicenter of a major empire that extended from presentday Iran to Egypt. In its final and most spectacular phase, the monument was built with brilliantly glazed bricks, molded in relief to depict hundreds of dragons, lions, and bulls—all set against a background the color of lapis lazuli. At once providing access to and protecting the heart of the sacred imperial city, these creatures inspired both admiration and apprehension.
By the late 19th century, it appeared that all that was left of the Gate were glittering fragments of colorful glazed brick scattered among the rubble of collapsed clay architecture. But between 1899 and 1917, German-led excavations not only studied the glazed remains of the towering Ishtar Gate, but also excavated its molded (unglazed) foundations, which extended deep into the earth. Archaeologist Robert Koldewey sent almost 800 crates of fragments to Berlin, with the permission of the Ottoman, and later the Iraqi governments. Once there, the colorful remains were cleaned, stabilized, and sorted, then assembled piece by piece, creating first whole bricks and subsequently panels of brightly colored raised-relief beasts. These reconstructed ancient remains were joined with modern blue bricks to create a monumental reconstruction (albeit at a slightly smaller scale) of the Ishtar Gate and its affiliated Processional Way at Berlin’s Vorderasiatisches Collection, housed in the Pergamon Museum.
Today, a multi-national process of excavation, reconstruction, and conservation of the Ishtar Gate continues, both on-site and at various institutions. The monument may be experienced not only in Berlin, but also at Babylon, Iraq—now a UNESCO World Heritage Site—where earlier phases of the Gate still stand and visitors can experience its true scale and relationship to the ancient city.
The objects on view in A Wonder to Behold are on loan from a variety of international and domestic collections including the Louvre, the British Museum, the Metropolitan Museum of Art, and, notably, the Vorderasiatisches Museum. Together, they provide a vivid picture of the making of the Ishtar Gate, shedding light on the people who created it and the materials they engaged with and transformed.
The exhibition opens with an introduction to the gateway as revealed through its discovery and reconstruction. A variety of archival drawings, photographs, and objects demonstrate the immense complexity of this undertaking. A 1901 watercolor by archaeologist Walter Andrae, for example, shows the Babylonian system of fitters’ marks that he deciphered, revealing the painstaking process through which the monument was created. This process began by marking out the design on a wall of unadorned bricks, and continued with the molding, glazing, and baking of each individual brick before fitting them together, a task that is something like designing and assembling an intricate puzzle.
The Ishtar Gate and Processional Way represent the epitome of major developments in molding and glazing technologies that had taken place over the preceding centuries, enlivening architecture by bringing color and dimension to otherwise unadorned mud brick buildings. A reconstructed panel on view here shows one of the 120 molded and glazed lions that paraded out from the Gate and down the Processional Way. Believed to be powerful beings associated with the king’s role as protector of his people, the beasts are depicted in bold relief, projecting into the space of the viewer as they intimidated unwelcome visitors while protecting the inhabitants of the city.
Other objects illustrate the links between the world of the gods and the Ishtar Gate through an exploration of the religious meaning of lions, bulls, and mushussu-dragons. These include an Assyro-Babylonian cylinder seal showing the fierce goddess Ishtar, who helped protect the city from enemies, with her lion, and a marble bowl dating from 2900–2600 BCE that demonstrates the continuity and ritual significance of the repeating bull image—which also appears on the facade of the Ishtar Gate—and its ritual significance, already understood to be ancient in Nebuchadnezzar II’s time.
The material components of the Ishtar Gate and Processional Way—clay and a glass-like glaze composed of ground stones and metal oxides—were endowed with metaphysical and magical qualities. The exhibition examines these substances, including their origins, sometimes in far-flung places; the techniques with which they were produced and worked; and the powerful cultural and religious beliefs attached to them.
Endowed with vital power in the ancient Middle East, clay was viewed as the stuff of creation and tied closely to the gods: ancient texts asserted that the first gods and first humans were created of clay. Clay was often used to create figures believed to be imbued with life and capable of acting on their creator’s behalf. As highlighted by a mold for a female figurine here, artists in the ancient Middle East did not share the modern emphasis on the new, but frequently replicated more or less identical images, each thought to be as powerful as the next. As such, molds like this one were understood as authoritative image sources, originally passed down to humanity from the gods.
A Wonder to Behold also includes a fragment of a baked clay plaque with a striding lion reminiscent of those on the Processional Way. This piece, which dates from late 3rd–early 2nd millennium BCE, shows the longevity of lion imagery created from molded clay. Figures like these, which were believed to be capable of effecting change in the lived world, were not restricted to monumental or public contexts, but could also be found in domestic houses and shrines. Although their exact purpose is unknown, they may have protected the household from dangers such as illness and misfortune, as well as from demons, or they may have been directed to perform more specific magical tasks.
A brick from Babylon containing the cuneiform inscription of Nebuchadnezzar II illustrates clay’s inherent malleability and receptivity to touch. After being molded, bricks like these, which were used in official constructions, were stamped with the king’s inscription and laid out to dry in the sun or sometimes baked in a kiln. While this brick was still soft, it was also impressed with the paw of a wandering dog—a humble, everyday touch that gives us a direct, affective point of access to the ancient world.
A cuneiform tablet from the Middle Babylonian Period (ca. 1300–1200 BCE) records a recipe for making red glass that highlights the secret alchemical knowledge of ancient Middle Eastern craftspeople, while an Egyptian glass vessel from ca. 1400–1300 BCE showcases the range of brilliant colors that these experts were able to achieve. In fact, human-made materials were believed to be as powerful as naturally occurring ones, their brilliance and shine no less meaningful. The recipes for manufacturing these magical substances, which prescribed specific rituals to ensure a successful outcome, were closely held.
An ancient gilded coffin valued at about $4 million that was acquired by the Metropolitan Museum of Art was returned to Egypt in a repatriation ceremony Wednesday after prosecutors determined that it had been looted from the country.
Credit: Metropolitan Museum of Art
The coffin was the centerpiece of the Met’s exhibit “Nedjemankh and His Gilded Coffin,” which opened in July 2018.
“Coming as we do from all over the world, New Yorkers place a strong value on cultural heritage, and our office takes pride in our work to vigorously protect it,” Manhattan DA Cyrus Vance said at the ceremony attended by Egyptian Minister of Foreign Affairs Sameh Hassan Shoukry.
“Returning stolen cultural treasures to their countries of origin is at the core of our mission to stop the trafficking of stolen antiquities. I am honored to repatriate this extraordinary artifact back to the people of Egypt,” he added.
The District Attorney’s Antiquities Trafficking Unit — headed by Assistant DA Matthew Bogdano – and officials from Homeland Security Investigations followed a paper trail that raised several red flags about the coffin’s provenance.
Credit: WikiCommons
The forged May 1971 export license bore the stamp “AR Egypt,” referring to the Arab Republic — but at the time, the Arab Republic didn’t exist. The country was the United Arab Republic until September 1971, Vance explained.
In a joint probe with authorities in Egypt, Germany and France, officials executed a search warrant at the Met, which cooperated and handed over the ornate, mummy-shaped coffin, Vance said.
The coffin — which was crafted in Egypt in the first century BC — once contained the remains of Nedjemankh, a high-ranking priest of the Egyptian ram god Heryshef of Herakleopolis.
The coffin’s surface is decorated with scenes and texts in gesso relief that the museum has said were intended to guide Nedjemankh on his spiritual journey from death to eternal life, according to The Art Newspaper.
It was stolen from the Minya region of Egypt after the country’s 2011 revolution and smuggled to the United Arab Emirates.
It was later transported to Germany, where it was restored, and then to France, where it was sold by a Paris art dealer to the famed Fifth Avenue art museum in July 2017.
The museum has emphasized that all of the Met’s acquisitions undergo “a rigorous vetting process” that follows a 1970 UNESCO treaty, federal and state laws and the Association of Art Museum Directors’ guidelines, the news outlet reported.
“Today we are celebrating the return of one of our national treasures,” Shoukry said Wednesday. “It is not the protection of our heritage, but the protection of mankind’s heritage.”
In the ninth to seventh centuries B.C., the Assyrians, based in northern Mesopotamia (modern Iraq), forged a great empire that extended at its height from Egypt, Syria, Lebanon, Israel, Jordan, and parts of Turkey in the west, through Iraq to the mountains of Iran and Armenia in the east. To glorify their reigns, the Assyrian rulers built majestic palaces adorned with relief sculptures that portray the king as a mighty warrior and hunter, and confront visitors with imposing images of winged bulls, demons and other mythological guardians.
Assyria: Palace Art of Ancient Iraq, on view at the Getty Villa October 2, 2019 to September 5, 2022, presents a selection of these famous relief sculptures as a special loan from the British Museum in London. Among the greatest masterpieces of Mesopotamian art, the Assyrian reliefs have, since their discovery in the mid-19th century, fascinated viewers with their vivid depictions of warfare, hunting, building works, mythology, rituals, banqueting and other aspects of Assyrian court life. Often bearing cuneiform inscriptions, some scenes show characters, events and places known from the Old Testament and ancient Greek authors. Together they represent the richest body of narrative art and iconography to have survived from the ancient Near East.
“The British Museum possesses the largest and most important collection of Assyrian reliefs in the world. The fourteen panels on view at the Getty Villa create a compelling overview of the subjects, styles, and artistic achievements of Assyria’s sculptors, including outstanding masterpieces such as the ‘Banquet Scene’ of the last great king of Assyria, Ashurbanipal, reviled as ‘Sardanapalus’ in the Old Testament,” says Timothy Potts, director of the J. Paul Getty Museum.
“At the time of their discovery, taste in Britain—and Europe generally—hewed strongly to classical models, by which standard some saw these Assyrian monuments as unrefined; but this attitude soon subsided, and they are now universally appreciated as artistic achievements of great visual and emotional power. In our own day the historical and cultural importance of these sculptures has increased with the tragic destruction by ISIS of many of the reliefs that remained in Iraq. We hope therefore that this display will raise awareness of the need to protect major heritage sites that remain at peril around the world.”
The Assyrian heartland lay astride the Tigris River in Mesopotamia, in what is today northern Iraq. The reliefs in this exhibition come from the palaces of kings Ashurnasirpal II (883–859 B.C.) and Tiglath-pileser III (745–727 B.C.) at Kalhu (Nimrud), Sargon II (722–705 B.C.) at Dur-Sharrukin (Khorsabad), and the last great Assyrian king Ashurbanipal (668–627 B.C.) at Nineveh.
In the mid-eighth century B.C. the Assyrian Empire expanded westward to the eastern shore of the Mediterranean and Egypt, coming into contact with the Greeks in Phoenicia, on Cyprus, and along the southern coast of Anatolia (Turkey), as well as in trading colonies in northern Syria.
Assyrian palaces were imposing complexes that served both as residences for kings and their families and as the venues for official diplomatic and ceremonial functions. The most important rooms within the palaces were decorated with reliefs. Scenes in the throne room and reception halls typically emphasized the king’s military prowess and his status as the all-powerful ruler, sometimes in graphically brutal terms. The king’s private quarters could include beneficent mythological creatures, rituals, and other themes. The hunt was one of the most frequently depicted royal activities, symbolizing the king’s supreme power over the most fearsome enemies.
The British adventurer Sir Austen Henry Layard (1817-1894), who led the excavations at Nineveh and Kalhu (modern Nimrud), published two series of folio-sized illustrations documenting his discoveries under the title The Monuments of Nineveh (1849-1853). Both series are on display in the exhibition, the complete sets of images being accessible on an iPad in the gallery. A number of reliefs on view in the exhibition were excavated by Layard in 1845-51.
This is the second long-term loan exhibition in the gallery devoted to The Classical World in Context, a new gallery at the Getty Villa highlighting cultures that influenced and interacted with the classical world of ancient Greece and Rome.
The exhibition will remain on view for three years, during which it will coincide with upcoming exhibitions on ancient Mesopotamia (March 18 – July 27, 2020), drawn from the collections of the Musee du Louvre, and ancient Persia’s relationship with the classical world (2021).
Assyria: Palace Art of Ancient Iraq is curated by Timothy Potts, director at the J. Paul Getty Museum, with assistance from Sara E. Cole, assistant curator of antiquities at the J. Paul Getty Museum.
The real Jurassic Park was as an ancient landscape home to a vast desert covered mostly in sand dunes as far as the eye could see, where dinosaurs and small mammals roamed southern Utah. The Navajo Sandstone is known for its beautiful red and tan crossbedded sandstones that grace many of the national parks and monuments in the southwest USA--for example Arches, Canyonlands, Capitol Reef, and Zion national parks.
Navajo Sandstone from the Moab area [Credit: Stephen T. Hasiotis]
The sands were deposited in dunes within the largest known sand sea (erg) in Earth's history during the Early Jurassic. These deposits show a record of desertification--the process by which fertile lands become desert. How did this landscape lose its water bodies, vegetation, and animals? How long did desertification take to happen? How long did it last? What amount of time is actually represented by these deposits? Understanding the timing, scale, and duration of this significant period in Earth's history is challenging, and many questions are unanswered due to the lack of age constraints in these deposits.
A new study by Parrish et al., published in Geology, has determined numerical ages from several calcium carbonate (i.e., carbonates, CaCO3) rock layers that represent lake deposits that once occupied interdune areas, which served as watering holes for a variety of dinosaurs and small theraspids (relatives of mammals). These carbonates were age dated using the radiometric method of uranium-lead (U-Pb), providing ages of 200.5 ± 1.5 million years (Ma) and 195.0 ± 7.7 Ma.
These age dates show that in eastern Utah parts of the Navajo desert are much older than previously thought, and together with age dates from Arizona show that the giant sand sea became younger to the south. The lake and associated spring deposits also show that this vast desert, at times, had a wetter climate and more active hydrologic cycle than had been previously assumed.
This work demonstrates that the desertification process is complex, and that age dates from carbonates and correlation of rock layers will help answer major questions of how desertification takes place in continental interiors.
This study has societal relevance because the history of hydroclimate (i.e., groundwater and climate) change recorded in the Navajo desert deposits can serve as a model for modern marginal environments that may be impacted by desertification from a warming climate.
With the projected rise in global temperature, regions in marginal zones are anticipated to become even more vulnerable to desertification. That is, these zones will become part of the growing desert regions. Particularly vulnerable areas are found in Africa and Asia, areas with large population densities that are already exceeding the capacity to supply food and water. By studying how the Navajo erg evolved, we can provide important insights into rates of modern desertification.
