ARCHAEOLOGY, TOOLS, METHODS, DATING AND ANALYSIS

ARCHAEOLOGY

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Opening King Tut's tomb
Archaeology is the study of historic or prehistoric people and their culture through the study of their artifacts, monuments and other items they left behind. The word archaeology is derived from the Greek words “archeo,” meaning “chief” and “ology” meaning “study of”.

Many archaeological sites are discovered accidently, often during construction projects. Some archaeologists call what they do as “running in front of bulldozers to retrieves objects before construction at a site begins.” Other are uncovered by following clues in historical records or digging where mounds and ruined buildings have been found.

On modern archeologists, the German film director Werner Herzog told Archeology magazine, “It's quite extraordinary what they are doing now. How they have new, almost forensic-like science to collect pollen and understand the vegetation. They do things that are unprecedented, in a way, and it's very beautiful to see that. I'm really intrigued by modern-day archaeology. For example, a square foot in one of the caves in the film — it took five months to remove half a centimeter of sediment. Every single grain of sand was picked up with a pair of pincers and documented with laser measurements. And all of a sudden it makes clear things like the flute, the flute from Hohle Fels Cave [in Germany], which is mammoth ivory, and the tiny fragments that were not understood for decades, but they were preserved. That's a fine thing, yes, until somebody came who had the kind of imagination like the young woman who is in the film, Maria Malina, an archaeological technician who had the insight and started to put the fragments together.

See Hominids and Early Man

Good Websites Archaeology News Report archaeologynewsreport.blogspot.com ; Anthropology.net anthropology.net : archaeologica.org archaeologica.org ; Archaeology in Europe archeurope.com ; Archaeology magazine archaeology.org ; HeritageDaily heritagedaily.com; Livescience livescience.com/

History of Archaeology

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Early work in Mesopotamia
Looting ancient sites and digging up graves to find treasures has been around since the beginning of civilization but painstakingly excavated sites and carefully studying what is there — archaeology, in other words — is a relatively new idea.

The modern science of archaeology was invented in the 17th century. Early pioneers included Jacob Spon (1647-1685), a century physician who traveled throughout Greece and Asia Minor, comparing sites with historical texts, and J.J. Winckelmann, who wrote “ History of Art of Antiquity” in 1764.

See Pompeii, Troy, Mycenae.

Many objects obtained in the Middle East were obtained through the Ottoman patronage system. See Iraq.

Andre Lero-Gourhan revolutionized the practice of excavations by recognizing that vertical digs destroy the context of a site. Over 20 years (1964-1984) he and his students painstakingly excavated “scraping away the soil in small horizontal squares and making notes of where everything was located” the 12,000-year-old site of Pincevent, offering of the most detailed picture up to that point of life in the Paleolithic period.

Drawing Clues from Archaeology

Archaeologists attempting to piece together the past from poetry shards and piles of stones. They dig into the earth — a process known as excavating’searching for artifacts (objects) from an ancient people and try to date and figure the significance of these artifacts. Context is critical to understanding the significance of artifacts. This determined by the position of excavated objects compared to other objects and the remains of buildings and other structures. Archaeologists seek out trash dumps, which often contain vital clues to unmasking everyday life. The fact that archaeologists are much more skilled at gleaning large amounts of information from ancients scraps that previously would have been discarded has meant that process of excavating take much longer. Ancient people rarely threw out what was valuable to them. Things like jewelry and crafts are often found in graves but they have often already been taken by graverobbers and looters.

Most of things that we know about everyday life in ancient times has been determined by looking at scenes depicted on vases, examining tools, remains and artifacts left at archaeological sites and drawing clues from literary and historical texts.

The age of an individual died can be determined by looking at the knitting of the suture on the cranium, which closes as people age, and by noting how worn the teeth are. Children can be aged by which teeth have emerged from the jaw. Pitted tooth enamel is an indicator or starvation and malnutrition. The easiest way to determine sex is by examining the pelvic bones. Females have large round openings, large enough to accommodate the head of a baby. Males have a heart-shaped opening.

Nature of Archaeological Evidence

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David Silverman of Reed College wrote: “What kinds of questions does archaeological evidence answer? It tells us certain things definitively: where people lived; what kinds of houses they lived in; how many of their houses were clustered together (in other words, the size of their villages) and how close or far apart from one another they lived; what they ate (based upon the analysis of animal and fish bones in their garbage heaps); how they disposed of dead people; and what kinds of implements they used, especially pottery, stone objects, and weapons. There are some other kinds of questions about which archaeology gives us clues but no definitive answers. [Source: David Silverman, Reed College, Classics 373 ~ History 393 Class ^*^]

“The laws of physics determine what sort of objects survive in the ground through centuries of time. Dry climates and sandy soils preserve delicate materials better than wet climates and muddy soils; this is why the vast majority of preserved papyrus fragments from classical antiquity come from the dry sands of Egypt. The possibility of preservation also depends on the material. Wooden objects and wooden structures in most circumstances do not survive very long (although wood does survive better in wet conditions than dry, and the wooden hulls of ships are sometimes preserved for thousands of years under the sea floor). ^*^

“Many buildings in antiquity had stone foundations (which do survive) and wooden superstructures (which do not). Neither do paints last; the temples and other public buildings which we are used to thinking of as being the color of marble were in fact brightly painted, as were marble statues. Metal objects have a better chance of surviving; a relatively small number of bronze and iron objects have survived from antiquity, often in a state of advanced corrosion. In particular circumstances (such as if the ground is frozen, or the item is sealed in an airtight container) cloth or leather items may survive.” 8^*

Archaeology Techniques

Archaeologists crawl, kneel and laboriously brush away dirt with a brush from objects they unearth. Soil, sand and excavated material are sifted through screen to retrieve small artifacts.

Archaeologists often dig a series of trial trenches to figure out the best places to excavate. Photographs are taken of each phase of the work for future reference. Soil is sifted so that small objects are not overlooked. When something is found it is often swept with a brush and removed with a trowel so it doesn’t break.

Artifacts are brought into workshops are catalogued. Delicate objects are restored in situ. Other objects are restored in the work room or laboratory. Bronzes and other objects are often restored with distilled water, which does not remove the patina (the thin coating that forms on stone, ceramic or metal over centuries). The patina us often checked to determine whether an object is real or fake. Pots are restored by removing old varnished made from glues made from animal hooves and applying sealants that do not become discolored.

Book: “ Written in Bones: How Human remains Unlock the Secrets of the Dead” by Paul Bahn

Archaeology Layers and Positions

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It is very important to record the position of all the objects that are found. The vertical position of an object, as defined by the layer in the earth, or strata, where it is found reveals its date or at least it relations to what came before and after it. Archaeologists carefully remove earth layer by layer when they are excavating so they can determine the date or period of objects and not mix them up with objects from other periods.

The strata are often look like the layers of a layer cake, with the oldest layers being the ones that are the deepest in the earth. Each layer and the locations of artifacts are carefully measured, often with surveying equipment. The layers can be dated by using the dating methods listed below.

Many ancient buildings were constructed of mud brick or stone. Over time, walls of these structures tended to weaken and collapse, often due to rain or an attack, and the ruins were leveled off before a new structure was raised. Each time a building collapsed and a new one was built on top of it and a new layer of strata was created. Over centuries many layers are piled on top of one another and a mound is created.

The horizontal position of an object and it locations in relation to other objects often give clues to what the object is used for. The locations of each significant object found are recorded using a grid system that usually can be overlaid on the excavation site. These days measurements can be done with lasers and excavation records and survey data can quickly be transferred to computer to create a three-dimensional model of excavated objects and their positions.

Stratification and Commerce

David Silverman of Reed College wrote: “The distribution of pottery types into particular layers of an excavation is not always perfect. Sometimes a single layer contains pottery from two different periods. Come back for a second to the hypothetical example of the Bell-bottom people versus the Saggers. Suppose you found a few pairs of bell-bottoms among the baggy shorts. Since they are relatively rare compared to the shorts, we can posit that a few people in the 1990's liked to wear clothes from the 1960's. The bell-bottoms might actually date back to the 1960's; the analogous pottery item in this case would be called an heirloom. Or, the bell-bottoms might have been made in the 1990's in a deliberate effort to achieve that 1960's look; the pot in this case would be called archaizing. [Source: David Silverman, Reed College, Classics 373 ~ History 393 Class ^*^]

“What if, on a level which had primarily bell-bottoms, some baggy shorts showed up? Or, in pottery terms, what if you find traces of a late style in a layer which the majority of the evidence suggests is early? This situation is much more rare than the previous one. There would be only two possible explanations. One, that the stratification of the site, the levels, had been disturbed at some time between the inhabitation of the area and the excavation. This happens when someone has dug through the levels and jumbled up their contents. If it is established that the levels were undisturbed, that means that the previously existing ruling chronological scheme, which maintained that no one was wearing baggy shorts in the 1960's, was wrong and has to be revised. Archaeologists tend to have a hostile reaction when someone claims that a particular pottery chronology needs revision.^*^

“In addition to knowing the date of manufacture of a particular piece of pottery, it is often also possible to tell where it was made. This in turn allows us to deduce with what other peoples a particular people might have had contact, especially commerce. Goods commonly traded in antiquity, such as wine and oil, were routinely transported in large earthen vessels, called storage amphoras. Sometimes, too, the vessel itself is the import product; this is true in the case of some elaborately decorated pottery (called fine ware, as opposed to coarse ware such as storage amphoras).” ^*^

Stone Tool Terminology

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Louis Leakey
Stone tools are the oldest surviving type of tool made by hominins, our early human ancestors. It is likely that bone and wooden tools were used quite early, but organic materials deteriorates with time and doesn’t survive like stone. Archaeologists sometimes use the term 'lithics' to refer to all artifacts made of stone. [Source: K. Kris Hirst, Thoughtco.com, March 8, 2017 ==]

Artifacts (also spelled artefacts) are objects or remainders of objects, which were created, adapted, or used by humans. The word artifact can refer to almost anything found at an archaeological site, including andscape patterns, trace elements attached to potsherds. All stone tools and pieces of stone tools are artifacts. ==

Geofacts are pieces of stone that looks as if they can be used as tools, with seemingly human-made edges, that have been created naturally by erosion or being broken and have not been shaped, modified or purposely broken by humans or hominins. Objects that are products of human behaviors are artifacts. Geofacts are produced by natural forces. Telling the different between artifacts and geofacts can often be difficult. ==

An assemblage or haul refers to the entire collection of artifacts recovered from a single site. Material culture is used in archaeology and other anthropology-related fields to refer to all the corporeal, tangible objects that are created, used, kept and left behind by past and present cultures. ==

Working on an Archaeological Dig

Describing his experience, working as a volunteer at an Early Bronze Age site in Mitrou, a small island in southern Greece, Stefan Beck wrote in the Wall Street Journal, “It was before six on my first morning...I found myself hauling potsherds, pickaxes, shovels and computers from a gecko-infested “apotheke” (warehouse) to a big orange truck parked outside. When the truck was full, we headed off, a police escort alongside to protect us from hijackers — that is to say, from antiquities smugglers eager for our loot. We then unloaded it at a new, more spacious apotheke.”

“The second day was spent removing backfill at the site. At the end of each season of exploration, the archaeologists put a tarp over the site and then covered it with soil to protect artifacts from the ravages of weather...here I began to grasp how little of archaeology is strictly “digging.” As the dirt came out these scientists paid careful attention to the profile of the tarp beneath it; even a after a year, the trench supervisor knew what lay under every contour — a cist tomb, a fragment of wall...The site operated as methodically as an ant arm and with every bit as much purpose.”

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“As the days wore on — and my back wore out — I became more impressed by the range of knowledge that mere “digging” required. Archaeology cuts across the shallow trench that divided the hard sciences from the humanities. To get the full value...requires some knowledge of technology, history, language (both ancient and modern), classical literature, zoology , botany, geology and art...And how can I forget the charming field of mortuary analysis.”

Pottery Analysis

Almost every archaeological site yields thousands of pieces of broken pottery known as pottery shards, or potsherds. Because pottery was cheap and easy to make, ancient people thought nothing of throwing it away. Archaeologists are adept at deciphering pottery shards. They can often date a site, gage its level of sophistication and establish trading patterns solely by examining pottery shards.

There are tables and guides that archaeologists can refer to identify potsherds. Different kinds of pottery can be differentiated by the designs, pottery making process and the composition of clay, glazes and pigments used to make it. Large data bases of over 7,000 kinds of pottery from different ages and different sites around the Mediterranean alone cane be used to identify the date and origin of the objects. The analysis is based on the type of clay used, pottery type and ornamentation.

Pottery can be dated measuring the effects of radiation via thermolumiscence, by carbon dating food remains or dating the sediments of the layers in which the pottery was found. A “clay atlas” has been created for “fingerprinting” pottery for 35 trace elements. This atlas is especially useful with small pottery shards.

Importance of Pottery

David Silverman of Reed College wrote: “One material which totally defies the corrosive effects of long periods of burial is baked clay. At almost every single place where humans have lived, from the Neolithic age on, remains of their pottery can be discovered. Pottery is enormously important to archaeologist, no only because of its omnipresence, but also because it permits them to answer another question with near certain exactitude: when did these people live? Pottery answers this question because people of different time periods and different cultures made different kinds of cups, pots, jars and so forth. Pottery varies according to the shape of the vessel, the type of clay, the nature of the decoration outside or inside the pot, and the technique employed for shaping and firing. [Source: David Silverman, Reed College, Classics 373 ~ History 393 Class ^*^]

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“Imagine that an archaeologist from far in the future was digging a late 20th century site, and that clothing served for him the function that pottery does for archaeologists of ancient sites. He finds two layers, each representing the occupancy of a space by a different group of people at a different time. In settlement "A" everyone wore bell-bottom jeans; in settlement "B" (which is closer to the surface than settlement "A") everyone wore big baggy shorts which reached to mid-calf. The archaeologist would then refer to an already established chronology based upon the preference for pants styles at other late 20th century American sites, and he would then be able to date settlements "A" and "B" within a margin of error of around five to ten years. And in fact a margin of error of ten to fifteen years is typical for dates based solely or primarily upon pottery evidence.^*^

“Pottery dating is not perfect. First of all, one might think when finding out for the first time about how important pottery is for archaeological dating, it is so low-tech. What about the analysis of the breakdown of radioactive isotopes, carbon 14 dating? Actually, carbon 14 dating tends not to be very helpful to archaeologists (more so to geologists and the like). Carbon-14 dating only works on items which contain carbon, such as wood or coal. And in some cases C-14 dating can tell you only when an object's raw material first came into existence, as opposed to what you really want to know, which is when the material was shaped into its current form.” ^*^

Written Sources and the Limitations of Archaeology

David Silverman of Reed College wrote: “What kinds of question can archaeology not answer? Perhaps this would be better phrased as, what kinds of questions can archaeology not answer as well as written sources? Archaeological evidence is less useful than written sources for figuring out what a group of people thought, what they believed, as well as for informing us about their political structures, about how societies organized themselves. Even so there are some peoples and some periods from antiquity, for which there are either no textual sources or only textual sources filled with guesses and false information. [Source: David Silverman, Reed College, Classics 373 ~ History 393 Class ^*^]

“This is essentially true for all of the non-Greek inhabitants of Italy down to the establishment of the Roman Republic in 510 B.C. In such cases archaeological evidence is pressed into service. For example, figurines presumed to represent deities spark inferences about the religious beliefs and practices of a people. Female figures with oversized breasts and hips, or large pregnant looking bellies, become fertility goddesses. This is useful up to a point but it can go too far, as when far-reaching theories about matriarchal societies are spun on the basis of statues of this sort. Likewise, if a settlement has one very large house or palace and a number of other smaller dwellings clustered around it, it becomes tempting to posit that the large house housed not only a king and queen, but also served as a center for worship and for the decision of judicial questions.

“So there is a delicate balancing act involved with interpreting archaeological evidence, just as there is with written texts; the methods, however, are dissimilar. In the first case the rule is, not to try to go beyond the conclusions which the evidence will reasonably allow. In the second case, the rule is to distinguish fact from fiction (fiction not being consciously presented as such by ancient historians) and to show how or why distortion has come in to the historical record. In the best case scenario, you are dealing with a period for which there is both archaeological and historical evidence, and the former acts a check on the latter. ^*^

“The Romans believed that King Servius Tullius ruled the city of the seven hills during the years 578-535, and that one of his greatest achievements was the construction of a massive fortification wall. But the archaeological record belies that claim. It proves that the wall which the Romans believed to be the work of Servius Tullius, which they called the Servian Wall, was in fact no older than the sack of the city by the Gauls in 390. This is only one of many such cases involving buildings and monuments falsely attributed to the kings. Does this mean, then, that we cease to believe in all of the other acts, many of them not verifiable by the use of archaeological evidence, which were attributed to Servius Tullius?” ^*^

Genetics and Linguistics

Genetic studies of ancestry are based on observations of mitochondrial DNA. Unlike chromosomal DNA, which changes when sperm and an egg fuse, mitochondrial DNA is passed on only by the mother, unchanged and unaltered, except for occasional mutations, which occur every several thousand years or so and provide distinctive markers from which common ancestry can be traced. The more differences there are between samples, the longer ago they diverged. In this way mitochondrial DNA not only indicates how similar or dissimilar two people are but also indicates how far one must go back to find a common ancestor.

Geneticists studying the DNA of different groups focus on the Y chromosome, which is passed on along the male line with no input from mothers and thus offers clues of the ancestry of the group being studied. To study the DNA of an individual, DNA is taken from blood (if available) or available tissues, hair or even bone. Enzymes are added to isolate specific regions of the Y-chromosome DNA that are to be analyzed and studied.

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Human-Neandertal mtDNA

Geneticists have a strong interest in microsatellites, short section of junk DNA that mutate more rapidly than long section and do so at a constant rate, providing a kind of clock allowing scientists date the age of certain chromosomes and use that information to figure when certain populations emerged.

Most western Europeans carry a Y-chromosome-type marker called M173. Studies of microsatellites indicate that the individual who originated M173 lived 30,000 years ago. Most Middle Eastern men carry the M89 Y-chromosome marker, which is dated to 45,000 years ago, and M172 marker, which dates back to 12,000 years ago.

By studying commonalities between languages, linguists can go back in time and figure out which people are related to each other and when. Sometimes they identify key words and work look for similarities and work their way backwards in a way that is not unlike that of geneticists.

These days physical scientists often outnumber archaeologists at archaeological sites. There are botanist, zoologists, chemists, and scientists

See Hominids and Early Modern Man

Book: “ Lost Languages; the Enigma of the World’s Undeciphered Scripts “ by Andrew Robinson

Modern Archaeological Techniques

Sites are located with ariel surveys and satellite imagery. Satellite images sometimes reveals the outlines of temples, towns and trade routes obscured by sands or vegetation cover or sites that are otherwise missed on the ground. Multi-spectral light-imaging technology, designed for NASA for the study on planet surfaces, has made it possible to read papyrus scrolls badly burned in the eruption of Pompeii. Using extremely sensitive filters, scientists are able to see black ink written on the burnt black papyrus.

Sometimes small camera are inserted into tombs. First a hole is drilled and a tube is inserted and the camera is inserted through the tube. An effort is made to make sure the interface is airtight so that no air or contaminants enter the burial chamber.

Magnometers and metal detectors are used to search for metal objects under the surface. Archaeologists can also send electric currents through the ground at depths of a few foots. By observing differences in the resistance to current they can record differences in subsurface densities and determines what is below: foundations, pavement or just dirt. This helps locate buildings and determines the lay out of settlements.

Ultrasound and seismic generating machines are now being used by Egyptologists to locate temples and ruins covered by sand. Scientists are also using theodolites, electric distance measurers and the technique of photogrammetry. They shoot seismic waves through the sand and the through the monuments. Magnetometers are used to detect tombs. The underground radar does not work well when water is present.

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CT scan for the Iceman
Mummies are being scanned with CT (computerized tomography) technology to determine their age, sex and cause of death and whatever else can be gleaned from them. With this technique the mummy is X-rayed at different angles to produce a 3-D composite image of the entire body. One advantages of such scans is the mummy does not have to be unwrapped. The details are better than those of X-rays. Using this technique archaeologists and specialists check for evidence of trauma, vitamin deficiencies, degenerative diseases.

Foods and drinks from ancient times can be determined by analyzing samples in a spectrometer and looking for organic compounds, especially long-chain lipids, triglycerides and fatty acids that characterize many foods. The presence of beer can be determined by the presence of calcium oxalate (“beerstone”). Wine can be determined by tartaric acid and its salts. Samples can be extracted from pottery and jars with solvents. Specific fatty acids can be markers for meat such goat, mutton and pork. Anisic acid is an indicator of anise, or fennel.

Pollen grains of specific species have vary distinctive shapes and surface patterns. They can be easily identified under a microscope and scientists can use them to date objects and describe the habitats of objects that contain them. By identifying ancient seeds and pollen archaeologists can figure what people ate and drink and get some insight into weather patterns in ancient times. Archaeologists can also figure out trade patterns by analyzing the chemicals in paint and vegetable dyes found in scraps of clothes.

Underwater archaeologists use sonar and multibeam bathymetric technology to scan the sea floor and send down remote control camera. Doing excavations of shipwrecks and ruins below about 50 meters is very difficult and expensive because those depths are beyond the reach of divers who can work any great length of time. See Bronze Age Ship, Romans, Greeks

Dating Methods

Historical records only go back to around 2000 B.C. Dating of ancient Egypt, and Sumer was done by examining written records of the durations of reins of kings. By working backwards archaeologists came up with the date of 3000 B.C. when those civilizations first evolved.^^

Ancient icons are indispensable archaeological tools. Minted to record a major historical event or the deification of an emperor of major figure, they can help scholar date objects and layers with some precision and provide important information on trade and political ties. Coins are used in a similar fashion. The oldest coins with dates to around 700 B.C.

Sometimes geologists can help date objects by measuring the amount of rain wear in cracks, alluvial deposits by streams and glaciers and layers of silt in lakes. Lichenometry is useful in measuring lichens from 100 and 9,000 years old.

Alexander Marshak identified the Ishango Bone. Afterwards he investigated scratched pebbles and other materials from the last Ice Age in EUROPE and discovered inconclusive evidence of time-keeping [time factoring] as far back as about 45000 years.

See Pottery, Above

Thermolumiscence and Optically Simulated Luminescence

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australopithecus sediba endocast
Thermolumiscence counts the number of electrons trapped in the microscopic crystal structure of a burned flint tool or other objects that to have been exposed to early-man-produced heat. By measuring the trapped electrons, the time when an object was last heated can be estimated. The method is useful in measuring minerals and natural glass between 0 and 500,000 years old.

The science behind thermolumiscence is the following: When minerals and natural glass are heated to a certain point radioactive atoms surrounding and buried inside crystals can release particles than can knock electrons out of their orbits. The released electrons sometime get stuck in defects in the crystal structure and over time the crystal fills with electrons at a regular, measurable rate. The trapped electrons are measured by reheating the material. As the trapped electrons escape they release light. By measuring that light scientists can count the trapped electrons and determine the age of the material.

Optically simulated luminescence is used to determine when minerals such as quartz are buried under sand or sediments by determining when they were last exposed to sunlight. This method operates under the same principals as thermolumiscence: by measuring the trapped electrons, the time when an object was last exposed to sunlight can be estimated. The trapped electrons are measured by firing beams of photons at the object. As the trapped electrons escape and return to their atoms they release heat. My measuring the heat scientists can count the trapped electrons and determine the age of the material.

Optically simulated luminescence is useful in measuring minerals and natural glass between 0 and 500,000 years old. The trick is to find objects that have not been exposed to sunlight and prevent them from being exposed to sunlight. Just of few seconds of exposure to sunlight can cause the trapped electrons to break from the crystals and return to their original state. Scientists who rely on this methods can not look for fossils and objects in the normal way in the sunlight. They hammer hollow, stainless steel cylinders into the sand and capped them and later examine their finds in a darkroom and fire beams of photons their samples to release the trapped electrons.

Carbon 14 Dating


taking a sample of a mummy's tooth

Carbon is useful in measuring minerals, shell, bone, wood, teeth and charcoal between 0 and 40,000 years old. After a living things dies that ratio of carbon 14 isotopes to carbon 12 isotopes decays at a known rate. By measuring the change in ratio of unstable carbon 14 to stable carbon 12 an organic material can be dated. Fossils over 40,000 years have so little carbon 14 left the method is no longer accurate.

Radiocarbon 14 dating was pioneered in the 1940s by University of Chicago chemist Willard Frank Libby, who won the Nobel Prize for his work. Carbon 14 is an unstable radioactive isotope produced when cosmic particles from space slam into nitrogen atoms in the upper atmosphere. Living plants and animals absorb Carbon 14 and other kinds of carbon from carbon dioxide in atmosphere.

When a plant or an animal dies it can no longer absorb carbon. The carbon 14 then begins to revert back to regular carbon (Carbon 12) at a known rate. The amount of Carbon 14 in a sample can thus be used to determine the date the sample died, or in other words when it stopped absorbing carbon.

Carbon 14 has a half life of 5,730 years. This means that after 5,730 years the amount of carbon 14 in an object is reduced by half as the carbon 14 changes to nitrogen 12. After another 5,730 years half of the remaining amount of carbon 14 decays by half again so that only one quarter of the original amount is left — and so on until about 40,000 years when only negligible amounts of carbon 14 is left.

With Carbon 14 dating, a sample of the material to be dated — for example, charcoal from a hearth, a piece of wood from a ship beam, a seed in a strata of soil — is burned and reduced to pure carbon. The ratio of Carbon 14 to Carbon 12 can be measured with a high energy mass spectrometer, revealing the date. Carbon dating can be used to date even minute samples of something such as residue on pots or pigments.

Problems with Carbon Dating

David Silverman of Reed College wrote: “Carbon 14 dating tends not to be very helpful to archaeologists (more so to geologists and the like). Carbon-14 dating only works on items which contain carbon, such as wood or coal. And in some cases C-14 dating can tell you only when an object's raw material first came into existence, as opposed to what you really want to know, which is when the material was shaped into its current form. [Source: David Silverman, Reed College, Classics 373 ~ History 393 Class ]

Over the millennia the amounts of Carbon 14 in the atmosphere have not been constant. This means that in certain period a given organism can absorb more or less Carbon 14 depending on how much is in the atmosphere. Fortunately some trees, such as bristlecone pines in California live a long time, and their ages can be accurately measured using tree rings and Carbon 14 levels can be measured in each tree ring and thus a table has been produced that compensates for fluctuations in Carbon 14 levels during each year.

Short-lived plants such as grain are the best for dating. With wood there is always the problem that the tree was cut down long before it was incorporated into a site. In addition, Carbon 14 levels often vary greatly depending on which part of the tree the sample came from: deep inside the tree or on the outside.

Samples can also be contaminated with younger or older carbon brought it by groundwater, earthquakes or carbonate rocks such as limestone. Contamination can usually be eliminated with careful cleaning before the dating process begins. Even when all goes well, the dating does not produce a date but rather a probability that the sample falls within a certain range of dates.

Nondestructive Radiocarbon Dating

Nikhil Swaminathan wrote in Archaeology magazine, “Precisely dating archaeological artifacts is not as easy or harmless as it might seem. The most common method, radiocarbon dating, requires that a piece of an organic object be destroyed — washed with a strong acid and base at high temperature to remove impurities, and then set aflame. The resulting release of carbon dioxide is fed to an accelerator mass spectrometer, which measures the decay of radioactive carbon 14 — the more the carbon 14 has decayed, the older the object is. [Source: Nikhil Swaminathan, Archaeology magazine, January/February 2011]


accelerator mass spectrometer, machine used to measure the carbon 14 decay in a sample

Over the past 20 years, chemist Marvin Rowe of Texas A&M University has developed a nondestructive method for carbon dioxide extraction. In his process, an object is placed in a vacuum chamber and a supercritical fluid---a hybrid gas/liquid---is applied as a solvent (as in dry cleaning). Next, Rowe passes plasma---an “electrically excited ionized gas”---over the artifact, which selectively strips carbon from the sample. “It’s essentially like slowly burning the sample, so we can just oxidize a little off the surface and collect that carbon dioxide,” explains Rowe. This year he further refined the method so it will work on objects coated in sticky hydrocarbons, such as the resins that cover Egyptian mummy gauze.

Thus far, he’s dated samples of wood, charcoal, animal skin, bone from a mummy, and ostrich eggshell. “Everything so far that we’ve tried to do with the nondestructive technique has agreed statistically with regular radiocarbon dating,” Rowe says, “and you basically don’t see any change in the sample.” R. E. Taylor, a radiocarbon expert at the University of California, Riverside, says Rowe’s technique may have limitations, as items older than 10,000 years will have impurities that the technique may not be able to purge. Archaeologists, meanwhile, are hailing the discovery as one of the most important in decades, particularly for issues surrounding the repatriation of human remains from Native American burials, which modern tribes don’t want to see harmed.

Rowe’s refinement of carbon dioxide extraction dovetails with an update to the radiocarbon calibration curve, which increases the accuracy of radiocarbon dating by accounting for past fluctuations in carbon 14. According to researchers at Queen’s University of Belfast, the new curve doubles the accuracy of dating as well as the age of artifacts on which it can be used, from 25,000 to 50,000 years.

Normally carbon samples are converted to acetylene gas by combustion in a vacuum line. The acetylene gas is then analyzed in a mass spectrometer to determine its carbon isotopic composition.

Tree Rings


bristlecone tree rings

Dendrochronology is useful in measuring tree rings from zero to 12,000 years old. Tree rings from bristlecone pines provide scale for correcting radio-carbon dating.

Every year trees lay down two layers — one broad and light colored during the growing season, the other dark in the winter when little growth occurs. The rings are not only useful in measuring age but also offer clues to what happens in given years. Each cross section of tree trunk has a distinct pattern of tree rings. Sometimes the rings have unusual growth patterns that occur during a particularly hot winter or cold summer or an event like a volcanic eruption.

With pieces of wood from trees that have been dead for centuries or millennia archaeologists often look for unusual patterns that indicate an event — like a volcanic eruption — that occurred on a known date and then count the tree rings from that event to determine the date of the artifact.

Artifacts dated using tree rings include logs used in the tomb of King Midas of the Phrygians, cut in 718 B.C.; timbers from an Egyptian shipwreck that revealed a gold scarab with Queen Nefertari's name, cut in 1316 B.C.; and logs of bronze age houses in Acemboyuk and Kultepe Turkey, cut in 1752 B.C. and 1810 B.C.;

Many objects from the Mediterranean and Middle East have been dating by looking at structural timbers from trees that grew during the catastrophic eruption on the volcanic island of Thera in the Aegean Sea that occurred around 1500 B.C. and hurled vast amounts of material in the atmosphere and caused a cooler and wetter summer worldwide. Bristlecone pines from California and oak tress from Irish bogs have tree rings that are more tightly packed after the volcano erupted.

Wood doesn't preserve, stone does.

Determining the Age of Wine by Examining Traces on Potsherds

The earliest evidence of grape wine was found in clay pottery from Khramis Didi Gora, Georgia dated to to 6,000 B.C. Ashifa Kassam and Nicola Davis wrote in The Guardian: “A series of excavations in Georgia has uncovered evidence of the world’s earliest winemaking, in the form of telltale traces within clay pottery dating back to 6,000 B.C. [Source: Ashifa Kassam and Nicola Davis, The Guardian, November 13, 2017 +/]

“To explore whether winemaking was indeed a part of life in the region, the team focused on collecting and analysing fragments of pottery from two neolithic villages, as well as soil samples. Radiocarbon dating of grains and charcoal nearby suggested the pots date to about 6,000–5,800 BC. In total, 30 pottery fragments and 26 soil samples were examined, with the inside surface of the pottery ground down a little to produce a powder for analysis. While many of the pieces were collected in recent excavations, two were collected in the 1960s; researchers have long suspected they might bear traces of wine.The team then used a variety of analytical techniques to explore whether the soil or the inner surface of the vessels held signs of molecules of the correct mass, or with the right chemical signatures, to be evidence of wine. +/

“The results, published in the Proceeding of the National Academy of Sciences, reveal that for eight of the fragments, including the two previously unearthed, the team found traces of tartaric acid – a substance found in grapes in large quantities. Tests on the associated soils largely showed far lower levels of the acid. The team also identified the presence of three other acids linked to grapes and wine. Other evidence indicating the presence of wine included ancient grape pollen found at the excavated sites – but not in the topsoil – as well as grape starch particles, the remains of a fruit fly, and cells believed to be from the surface of grapevines on the inside of one of the fragments. +/

“While the team note that it is possible that the vessels were used to store something other than wine, such as the grapes themselves, they note that the shape of the vessels is suited to holding a liquid and that grapes or raisins would have degraded without trace. Moreover, there are none of the telltale signs that the pots were used for syrup-making, while grape juice would have fermented within a matter of days. +/


accelerator mass spectrometer schematic for radiocarbon dating


Determining the Age of Cheese by Examining Traces on Potsherds

A study published in Nature in 2012 said that the earliest solid evidence of cheese-making comes from the chemical analysis on fragments from 34 pottery sieves discovered in Poland dated to 7,500 years ago. Maria Cheng of Associated Press wrote: “Though there is no definitive test for cheese, Richard Evershed at the University of Bristol and colleagues found large amounts of fatty milk residue on the pottery shards compared to cooking or storage pots from the same sites. That suggests the sieves were specifically used to separate fat-rich curds from liquid whey in soured milk in a crude cheese-making process. "It's a very compelling forensic argument that this was connected to cheese," Evershed said. "There aren't many other dairy processes where you would need to strain." He and colleagues weren't sure what kind of milk was used, but said there were lots of cattle bones in the region. [Source: Maria Cheng, Associated Press, December 13, 2012]

“"This is the smoking gun," said Paul Kindstedt, a professor of nutrition and food sciences at the University of Vermont and author of "Cheese and Culture." He was not involved in the study. "It's almost inconceivable that the milk fat residues in the sieves were from anything else but cheese," Kindstedt said, adding that many experts suspected cheese was being made in Turkey up to 2,000 years earlier than this latest finding in Poland but that there was no definitive proof.

Nature reported: “Peter Bogucki, an archaeologist at Princeton University in New Jersey, was in the 1980s among the first to suspect that cheese-making might have been afoot in Europe as early as 5,500 B.C. He noticed that archaeologists working at ancient cattle-rearing sites in what is now Poland had found pieces of ceramic vessels riddled with holes, reminiscent of cheese strainers. Bogucki reasoned that Neolithic farmers had found a way to use their herds for more than milk or meat. [Source: Nature, December 12, 2012 -]

“In a paper published in Nature, Bogucki and his collaborators now confirm that theory, with biochemical proof that the strainers were used to separate dairy fats. Mélanie Salque, a chemist at the University of Bristol, UK, used gas chromatography and carbon-isotope ratios to analyse molecules preserved in the pores of the ancient clay, and confirmed that they came from milk fats. “This research provides the smoking gun that cheese manufacture was practiced by Neolithic people 7,000 years ago,” says Bogucki. -

Strontium Isotopes

Isotopic studies of strontium and other chemicals found in the teeth and bones of Neolithic humans are helping archaeologists better track the movement of ancient peoples across the landscape. Strontium signatures last not just a lifetime, but potentially thousands of years as tooth enamel, the densest tissue in the body, resists decomposition and contamination after death. It is now commonly used by archaeologists to determine if an individual was local or foreign to the place where their remains were discovered.

According to a study of 5,000-year-old skeletons, being born to affluent parents meant something even in Neolithic times. Maev Kennedy wrote in The Guardian: “Hereditary wealth and privilege date back to the earliest days of farming in the Neolithic, according to researchers who have studied hundreds of ancient human skeletons. They found evidence that the wealth children were born into persisted right up to death and that rich people lived cheek-by-jowl with the poor – who scraped an existence from whatever they could find. "It seems who your parents were mattered even then," said Dr Penny Bickle of Cardiff University, one of the international team of researchers whose findings are reported in the journal Proceedings of the National Academy of Sciences. [Source: Maev Kennedy, The Guardian, May 28, 2012]

“The study looked at levels of strontium isotopes, which can reveal the diet eaten in childhood, in more than 300 skeletons dating from the Neolithic period, around 7,000 ago, from sites across central Europe. Some of the male skeletons were buried with stone adzes – cutting and chopping tools – which were often beautifully polished and made from carefully selected stone, and so were probably also symbols of status and wealth. An analysis of the strontium isotopes in their tooth enamel showed these individuals had lived on food grown in "loess", the most fertile and productive soil. ^=^

“Because strontium markers are laid down in tooth enamel in childhood, it seems they hadn't earned but inherited this richer diet, and the fact that they were buried with the adzes suggests that they died as they had lived: privileged to the end. "This strongly suggests that access to the best soils was being passed on between generations," Bickle said. "Thus, while I think it's not news that status differences and subsistence specialisms date to the Neolithic, this is perhaps the first time we've been able to show that inheritance was a large part of this." ^=^

Dating of a Variety of Materials from Different Ages

The following is a group of rocks and materials that have dated by various atomic clock methods (Approximate Age in Years, Sample material): 1) Cloth wrappings from a mummified bull, samples taken from a pyramid in Dashur, Egypt. This date agrees with the age of the pyramid as estimated from historical records 2,050, Charcoal) ; 2) Sample, recovered from bed of ash near Crater Lake, Oregon, is from a tree burned in the violent eruption of Mount Mazama which created Crater Lake. This eruption blanketed several States with ash, providing geologists with an excellent time zone (6,640, Charcoal); 3) Sample collected from the "Marmes Man" site in southeastern Washington. This rock shelter is believed to be among the oldest known inhabited sites in North America (10,130, Spruce wood); 4) Sample from the Two Creeks forest bed near Milwaukee, Wisconsin, dates one of the last advances of the continental ice sheet into the United States (11,640, Bishop Tuff). 5) Samples collected from volcanic ash and pumice that overlie glacial debris in Owens Valley, California. This volcanic episode provides an important reference datum in the glacial history of North America (700,000, Volcanic ash).

6) Samples collected from strata in Olduvai Gorge, East Africa, which sandwich the fossil remains of Zinjanthropus and Homo habilis — possible precursors of modern man (1,750,000, Monzonite); 7) Samples of copper-bearing rock from vast open-pit mine at Bingham Canyon. Utah (37,500,000, Quartz monzonite); 8) Samples collected from Half Dome, Yosemite National Park, California (80,000,000, Conway Granite); 9) Samples collected from Redstone Quarry in the White Mountains of New Hampshire (180,000,000, Rhyolite); 10) Samples collected from Mount Rogers, the highest point in Virginia (820,000,000, Pikes Peak Granite).

11) Samples collected on top of Pikes Peak, Colorado (1,030,000,000, Gneiss); 12) Samples from outcrops in the Karelian area of eastern Finland are believed to represent the oldest rocks in the Baltic region (2,700,000,000, The Old Granite); 13) Samples from outcrops in the Transvaal, South Africa. These rocks intrude even older rocks that have not been dated (3,200,000,000, Morton Gneiss); 14) Samples from outcrops in southwestern Minnesota are believed to represent some of the oldest rocks in North America (3,600,000,000).

Text Sources: National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Nature, Scientific American. Live Science, Discover magazine, Discovery News, Ancient Foods ancientfoods.wordpress.com ; Times of London, Natural History magazine, Archaeology magazine, The New Yorker, Time, Newsweek, BBC, The Guardian, Reuters, AP, AFP, Lonely Planet Guides, “World Religions” edited by Geoffrey Parrinder (Facts on File Publications, New York); “History of Warfare” by John Keegan (Vintage Books); “History of Art” by H.W. Janson (Prentice Hall, Englewood Cliffs, N.J.), Compton’s Encyclopedia and various books and other publications.

Last updated September 2018


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