If you&#;ve ever had the opportunity to view a panel of ancient rock art, I am sure you had many questions run through your mind. Who made these? What do they mean? When were they created? In modern archaeology there are many methods used to date rock art, but we will discuss a few that have been used in southeast Colorado.
There are a couple of over-arching methods archaeologists use to date rock art. The scientific methods can include cation-ratio (CR) dating, and varnish micro-laminating (VML) dating. The relative dating methods can include seriation, varnish repatination and superimposition. A few of the modern researchers that have utilized these methods in southeast Colorado include; Lawrence Loendorf, Julie Francis, and Ronald Dorn during their studies of rock art on the high plains. (Zier and Kalasz, )
(K+ + Ca2+)/Ti4+
&#;The premise of a new age-determination method, cation-ratio dating, is that the ratio of the more mobile cations (e.g., K and Ca) to titanium in varnish decreases with time. The method is only valid where manganese is not remobilized after deposition, for example, in most arid environments.&#; (Dorn, )
Cation-ratio dating is used to date rock surfaces such as stone artifacts and cliff and ground drawings. It can be used to obtain dates that would be unobtainable by more conventional methods such as radiocarbon dating. Scientists use cation-ratio dating to determine how long rock surfaces have been exposed. They do this by chemically analyzing the varnish that forms on these surfaces. (science.jrank.org, )
In addition to cation- ration dating in southeast, researchers have at times used accelerator mass spectrometry (AMS), a form of radio carbon dating, to gather data on the &#;minute carbon particles trapped beneath the varnish layer and the rock surface.&#; (Zier and Kalasz, ) To be more accurate, the cation-ratio dating is often used in conjunction with this AMS-derived data from the same rock surfaces to arrive at more absolute dates.
Studying the variations in a cross-section of &#;desert varnish&#; taken from a study site is the basis for varnish micro-laminating. &#;Microlaminations in rock varnish were first reported by Perry and Adams (), who recognized their potential as a paleoenvironmental indicator in drylands. Microlaminations can be observed when the varnish is shaved thin enough (5-10 µm) to see through in ultra-thin section with a light microscope.&#; (vmldating.com)
These variations can be indicators of drier and wetter periods in history allowing researchers to correlate rock art sites more accurately based on a wider base of knowledge such as regional historical climate studies. The varnish forms extremely slowly and different minerals and elements are captured at different times on the rock surface depending upon the climate at the time. At least that&#;s the theory. Of course, there are many debates about accuracy, but then the accuracy of nearly all modern scientific dating methods is often questioned. There are so many variables that can affect the end result. Often results are given a general timeframe of 100-200 years.
According to Cassells, &#;relative dating originated with Nicholas Steno who was one of the &#;fathers of geology.&#; In he published the Prodromus, which contained his observation that stratified sedimentary rock had its origins with horizontal layers, with the lowest levels older than the highest.&#; Assuming the soil formations follows the laws of superposition, it can usually be stated that the lowest cultural stratum is the oldest and the highest is the youngest. This is the simplest of the relative dating methods. (Cassells, )
Before there were scientific tests such as radio carbon dating and cation-ratio dating. Determining the date of an artifact depended upon its place relative to other information around it. Such as which layer the artifact may have been found in, context of where it was found, what else was found with it etc. These are called relative dating methods. In determining the age of rock art relative dating methods include seriation, varnish repatination, and superimposition.
Seriation is based on the assumption that artifact types have the equivalent of a life cycle. (Loendorf, ) In other words, rock art styles, symbols, etc. have trends. Just like hair styles &#; only, with probably a much longer staying power. The symbol or picture style starts, gains a high point of use, and then peters off as other styles gain use and popularity.
Seriation takes an inventory of similar rock art symbols or pictures and groups them together across many different panels. This is also called artifact sequencing. There are several types of seriation: frequency seriation, contextual seriation, evolutionary seriation, and similarity or stylistic seriation &#; based on different changes. (Archaeologywordsmith.com)
Seriations, in terms of rock art, are an organized look at types of rock art over time with variables such as image size, panel size, depth, varnish cover, density of rock art etc. These seriations can be used to analyze large quantities of rock art and get an idea of changing styles over time.
There is a great article on how Seriation works at this website:
Thoughtco.com/Seriation
Repatination refers to the re-coloration, or the re-growth of the desert varnish after a petroglyph image has been created. Repatination occurs at various rates and degrees. A close examination of the degree of repatination can give a relative idea of how old an image may be. A great degree of repatination (darkening) indicates greater age than an image that shows only slight repatination. (NPS.gov, )
There are times when rock art is drawn over the top of other rock art. This can help in the dating process of both petroglyphs. Lets take graffiti for example, it is often superimposed over more ancient drawings. Which is newer? Having two ancient styles or types superimposed can lend insight in the progression sequence of inscriptions.
In the photo above, there are four very faint white shields painted high on a canyon wall, over the top of some of them are red symbols. The red symbols are thought by some to represent various forms of fertility or growth. Does this symbolize a change in the people and religion now dominant in the area? We see through history how changes the ruling people also call for changes in religion. These new beliefs were often built on the foundations of the predecessors.
In addition to scientific and relative dating methods, there are times when a panel of rock art may seem to depict a historical or astronomical event. These can lend potential insight into the dating timeframe.
Possible Supernova Petroglyph at Chaco Canyon, Photo Credit: Laneha EverettExamples could include the possible &#;supernova&#; petroglyph at Chaco Canyon below Penasco Blanco. The people at Chaco would have had the opportunity to view two known historical supernova events in AD and AD. Since residents had begun building in the area in 900AD, it is possible that this petroglyph could represent one of these astronomical events.
More modern examples could include rock art panels that include depictions of horses. We know the horse was introduced in the early &#;s by the Spanish, most likely Cortez. As a consequence, we have a firm time line by which to then date these specific petroglyphs. We can possibly gain a more concise understanding of other petroglyphs on a related panel when used in conjunction with other scientific methods of dating. Depending on style of construction, superimposition, re-patination etc. we gain a better understanding of other petroglyphs that may be nearby.
There are many methods of attempting to date rock art. The ones included here are only a few. Scientific methods are continually being developed to gain more accurate data. However, on the whole no method is considered as acurate as using multiple methods to collaborate data. Scientific methods are used in conjunction with relative dating methods to gain a more acurate understanding of a site, panel or picture.
Archaeology Wordsmith, Seriation, https://archaeologywordsmith.com/search.php?q=seriation,
Cassells, Steve E., The Archaeology of Colorado, Chapter 4-Dating (pg 27-35),
Christian J. Zier and Stephen M. Kalasz, Colorado Prehistory; A Context for the Arkansas River Basin, Pg 52-55,
K. Kris Hirst, An Introduction to Seriation; Scientific Dating Before Radiocarbon, https://www.thoughtco.com/seriation-scientific-dating-before-radiocarbon-,
If you are looking for more details, kindly visit jm.
Lawrence L. Loendorf, Thunder and Herds; Rock Art of the High Plains, Pg. 33-43,
National Park Service; Petroglyph National Monument, Definitions; Repatination, https://www.nps.gov/petr/planyourvisit/def.htm),
Net Industries, Dating Techniques; Cation- Ratio Dating, https://science.jrank.org/pages//Dating-Techniques-Cation-ratio-dating.html,
Science Direct, Bruce A. Buchholz, &#; Kirsty L. Spalding, in New Perspectives in Forensic Human Skeletal Identification, https://www.sciencedirect.com/topics/medicine-and-dentistry/accelerator-mass-spectrometry,
VML Dating Lab, VML Dating: An Introduction, http://www.vmldating.com
In archaeological terminology, there are two categories of dating methods: absolute and relative. Absolute dating utilizes one or more of a variety of chronometric techniques to produce a computed numerical age, typically with a standard error. Different researchers have applied a variety of absolute dating methods directly to petroglyphs or to sediments covering them, including AMS (accelerator mass spectrometry) radiocarbon, cation ratio, amino acid racemization, OSL (optically stimulated luminescence), lichenometry, micro-erosion and micro-stratification analysis of patina. (See http://home.vicnet.net.au/~auranet/date/web/index.html for a summary and references). These techniques have yielded mixed results in terms of reliability and feasibility, but, in any case, none has been applied to date in Saudi Arabia. It is hoped that absolute dating will be successfully implemented in the future in this region.
Another way that precise dating can be achieved is if the artist records the actual date of his or her creation, the name of a leader of known reign, or a distinctive historical event, like the inscription shown in the previous chapter about King Yousif Assar Yathar&#;s invasion of the Najran region in 518 CE. Then, however, it must be clear that the artist is referring to his or her own time, and not providing historical commentary.
Given the current status of direct chronometric dating methods for Arabian petroglyphs, it is rare that the precise age of a rock art panel can be determined. However, all is not lost, and it is possible to establish a temporal sequence that can be quite edifying. To progress, it is essential to apply the second type, or relative, dating. The term refers to the fact that an approximate date can be inferred by comparison with something else of known age. In this case, a rock art panel may be judged to be younger, older or basically contemporaneous with another petroglyph, a site, an artifact, or other evidence of known antiquity. Relative dating, although somewhat less satisfying than absolute dating in terms of precision, is considerably more successful for petroglyphs.
Sometimes the proximity of a campsite or settlement that is dated directly by absolute dating methods is considered helpful for determining the age of an apparently associated petroglyph panel, but caution must be exercised, since it does not always mean that the site&#;s inhabitants were the artists who created the art. Often there are multiple sites of varying ages nearby and the petroglyph itself may be a palimpsest of images created through the ages.
On rare occasion, archaeological deposits can accumulate up against a petroglyph panel, concealing part or all of the art. In that case, it may be possible to discern a minimum age for the art because its creation had to precede the archaeological deposit covering it. This is not typical of the rock art in Saudi Arabia, however, which tends to be exposed and lacking any settlement or camp next to the cliff face.
Although it is difficult to state the absolute ages of most of the rock art studied in this project, there are certainly general trends, best estimates and bracketing dates, which will be provided whenever possible. Clues to relative dating include: the manufacturing technique used; the patina covering the art; the layering of figures on top of each other; the style of human forms; and the particular animal species, types of artifacts and subject matter shown.
For some 20,000 years, during the Late Pleistocene epoch (Ice Age), the Arabian Peninsula was overall very arid, as it is today. The earth at that time was considerably colder and the ice caps were much larger than they currently are. Many species, such as mammoth and woolly rhinoceros thrived in Eurasia and the mammoth, mastodon, camel and giant sloth lived in North America. Around 10, BCE, a significant climate change occurred, altering environments, flora, and fauna in most parts of the world.
Following the Pleistocene, the Holocene or Recent epoch, witnessed a marked global warming that we still experience today. The climate was not stable, however, and around BCE, monsoon patterns shifted northward, causing the Arabian Peninsula to be more like a savanna than a desert. Rivers flowed, lakes formed, and the human inhabitants, flora and fauna embraced this lusher environment. The Holocene Wet Phase, as it is called, fluctuated greatly between humid and dry periods and then reverted to a more consistent arid condition around BCE, as the rain belt retreated southward (Parker et al. ).
The oldest known petroglyphs in Saudi Arabia are believed to date to the Neolithic period or Early Arabian Pastoral, which appears to coincide with at least part of the Holocene Wet Phase. These images are typically carved or pecked deeply into the rock surface. Compared to subsequent periods, the older Holocene Wet Phase Neolithic images usually have a patina that formed after the art and is evenly dispersed over both the images and the background. Later petroglyph artists took advantage of desert varnish, a dark, often shiny glaze that forms on rock surfaces in very arid environments. By scratching through the varnish and revealing the lighter colored underlying rock, it was possible to create bold images. Many of the rock outcrops bearing Neolithic images never developed dark desert varnish at all. The uniformly light color of the sandstone surfaces explains why the Neolithic artists had to incise or peck the images deeply into the rock: so that sunlight raking across them would cast shadows demarcating the outlines of the figures.
The most common Neolithic scenes are of hunter-herders with bows and arrows and throwing sticks, which are similar to a boomerang. The hunter is usually aided by a pack of hunting dogs. Although these people were part-time pastoralists with herds of sheep and goats, the art suggests that hunting played an important role in their subsistence. The relatively high frequency of hunting scenes in contrast to pastoral ones could also reflect the greater risk invested in hunting forays, and therefore perhaps more accompanying rituals. Wild species targeted as prey by Neolithic hunters included: now extinct large-horned wild cattle, onager, ibex, bezoar goat, oryx, addax, and gazelle. A Neolithic scene at Shuwaymis illustrates a confrontation with a lion, but such depictions are more common in later periods. The leopard and cheetah are also shown on Neolithic panels at Shuwaymis, but not with the frequency of prey animals.
At least in Ha&#;il Province, Neolithic bow-hunters were typically portrayed in a set style, with an elongated rectangular head lacking facial features, an angular ponytail or feather projecting from the top of the head, and a sheath in the pubic region, tied in back.
Toward the end of the Holocene Wet Phase, the Chalcolithic period (4th millennium BCE) replaced the Neolithic. At the site of Jubbah, in the northern province of Ha&#;il, some of the images may date to this somewhat later period. Fairly realistic female figures at Jubbah, possibly Chalcolithic in age, are elaborately clothed in ornate dresses with a sash cinching in the waist to highlight their physique. They also lack facial features, although their hairstyles are more clearly depicted than for the Neolithic men. The method of creating the figures is constant, with deeply carved outlines and little or no removal of patina. Their antiquity is supported by the absence of associated horses, camels, or writing.
At the end of the Chalcolithic, the method of creating rock art shifted away from the laborious removal of large quantities of stone by making deep grooves and large recessed areas. After about BCE, when the Arabian Peninsula returned to extremely arid conditions, the rock surfaces in many areas started to form a dark brown to black desert varnish. These outcrops became the canvases of choice, since the removal of the thin veneer of desert varnish resulted in a high contrast between the subject and the background. Scratching through the thin surface patina revealed lighter-colored gold or pink sandstone beneath. The often dramatic images that resulted from this new technique highlight the outline or body of a figure by being lighter than the surrounding background. With this new method, the task of ancient artists was greatly facilitated, and they were able to create single figures or entire scenes relatively quickly. In contrast to the deeply incised Neolithic images, these shallower petroglyphs may fade more easily as patina gradually forms inside the subject area, rendering them less visible.
One of the chief subjects of research in this project was the response of animals and humans to the dramatic shift toward aridity after the Holocene Wet Phase. At the onset of the work it was hypothesized that the rock art might reveal significant changes in the frequencies of certain species, particularly medium to large wild herbivores. Unexpectedly, most of the prey animals and carnivores continued on in the rock art even with the return to an extremely arid climate. Only the wild cattle disappeared in petroglyphs and may have gone extinct in Arabia soon after the monsoon patterns shifted.
Otherwise, the biggest temporal change was the serial introduction of domestic livestock species. Distinctive domestic cattle with lyre-shaped horns and color patterns on their bodies appeared in the early part of the Arid Phase, after the wild cattle, their ancestor, vanished. It is likely that the images of early domestic cattle were produced in the 3rd-2nd millennia BCE since, based on patina on shared panels, they antedate cavalry, camels, and written text. As aridity increased, conditions would have gradually become less favorable for raising cattle in many areas. Still today, however, there are regions where cattle herding is feasible, especially those places that receive run-off from adjacent mountains or have a high water table and wells. The area around the modern city of Najran, in the southwestern part of Saudi Arabia, near the border with Yemen, is one such place.
The Late Bronze Age to early Iron Age is represented best by schematic images of chariots with a pair of four-spoked wheels, pulled by two horses. They are depicted in a fashion strikingly similar to the way artists showed them across Eurasia and North Africa, in aerial view, with the wheels lying flat and the horses in a recumbent position, either back to back or, more rarely, facing each other (MacDonald ). Although four-wheeled battlewagons and the peculiar two-wheeled straddle cars originated in Mesopotamia, the earliest actual two-wheeled chariots pulled by horses have been found in burial tumuli in Russia and Kazakhstan that date to around - BCE (Olsen ). It is therefore likely that the depictions in Saudi Arabia and North Africa are later, as this new innovation spread out from its source either in the Near East or the Eurasian steppe.
Later, in the Arabian Peninsula, as elsewhere, heavy chariots with more than four spokes in their wheels and up to three passengers are shown in a new style. Replacing the earlier aerial view, they are now depicted in profile, like those in Mesopotamian temple art. These date to the first millennium BCE, with the likelihood that actual horses and chariots belonged to or were acquired as war booty from Assyrian, Neo-Babylonian or Persian armies.
Horses with multiple features of the Arabian breed first appear in rock art in the northern part of Saudi Arabia. They are frequently accompanied by dromedary camels, as well as early Arabic script, such as Thamudic. The earliest firm date for Arabic writing (Thamudic B) also appears in the north, in the mid-sixth century BCE (MacDonald :14). However, inscriptions similar to those found near Tayma (Tamanite) have been found in Iraq and are dated by archaeological context to the 7th century BCE (Winnett and Reed :90). Thus, based on the associated writing, the earliest date we could comfortably assign to the Arabian horses is 7th-6th century BCE, unless and until evidence of earlier dates for writing is produced. The introduction of the Arabian horse breed in Egypt occurs in the New Kingdom, certainly by the time of Amenophis II (reign - BCE), if not earlier (Olsen ), most likely as war booty after successful engagement with Asian powers along the Levant. It would not be surprising, therefore, if evidence for Arabian horses that are contemporaneous with those of the Egyptian New Kingdom eventually emerges in Saudi Arabia.
It must be admitted that, as scientific evidence, artistic depictions are not on a par with actual skeletal remains of animals or real vehicles uncovered in excavations. Artists can return from distant lands where they witnessed foreign inventions or animals, or they can visually relate subjects that other individuals have seen elsewhere and described to them. Therefore, the artistic representations do not guarantee that the subjects depicted were actually present in that region. Also, artistic traditions can be tenacious, lasting decades or even centuries beyond an actual observation.
The Holocene Arid Phase, which continues today, led to a gradual shift in lifestyle and subsistence, from a nomadic life divided between hunting and herding to more full-time pastoralism. The arrival of domestic dromedary camels appears to have been a major contributing factor to this transition. As the oldest images of dromedaries are typically associated with Thamudic or other early inscriptions, the camel seems to have become significant only in the first millennium BCE. The earliest depictions of the distinctive breed of fat-tailed sheep also probably date to this period, particularly in the petroglyphs near Najran, in the southwest.
Still later, perhaps between the last half of the first millennium BCE and the first half of the first millennium CE, cavalry and battle scenes dominate petroglyphs. The most dramatic are to be found in the southwest, in Najran province, in a region known as Bi&#;r Hima. Also in this area, and in association with warriors, are female figures that have been interpreted as goddesses of fertility and war.
This temporal sequence is still in its preliminary stage of development and will undoubtedly be revised and supplemented as more information becomes available. However, it is already apparent that relative dating is extremely valuable and that it is often quite possible to place animal species and human activities in a sequence from early to late.
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