5 Exploration Techniques in Archaeology
V. N. Prabhakar
1. Introduction
Archaeology is a multi-disciplinary science drawing inputs from various disciplines to inquire into the human past on this planet. The period of investigation starts virtually since the appearance of ancestors of humans. The fossil human record in Africa is the most longest and continuous since around 4 Mya. The scope of archaeology when compared to history is vast and enormous as it investigates virtually 99.99% of human existence on this planet, whereas history only covers to the period in which written records are available. The scope of archaeology when compared to anthropology is often termed as ‘palaeo-anthropology’ or ‘past tense of cultural anthropology’ (Renfrew & Bahn: 2000). The cultural anthropologists study the present day living communities and draw their conclusions, whereas the archaeologists, through the material remains study the past societies. Archaeology is often compared with science, as it is more multi-disciplinary in approach, proposes hypotheses and test and validate them, often through laboratory work as done in other scientific disciplines. The macro and micro data obtained from archaeological excavations can now be investigated with the most sophisticated instrumentation and aspects like palaeo-diet, palaeo-climate, palaeo-migration, provenance studies, and others can be easily undertaken.
Looking into the history of archaeology, it can be understood that during the early phases of development, it was merely an act of discovery and treasure hunting and very less detailed documentation and interpretation until some of the most spectacular discoveries like Rosetta Stone in Egypt and decipherment of Egyptian hieroglyphs and Mesopotamian Cuneiform helped in the consolidation of this discipline. It is, therefore, an initial act of exploration, which helps in discovering archaeological finds and artefacts spread across the landscape, and often, deep forests. Scholars trace the beginning of modern archaeology to the period of Renaissance in Europe, during which an interest for collection of sculptures and artefacts and their study started (Renfrew & Bahn: 2000). Interest in the ancient past and their study grew in many parts of Europe and North America, which later followed by expeditions with objectives of understanding a particular culture and history. The investigations in Egypt and Mesopotamia and other parts of the ‘Old World’ gain momentum during 18th century. In the Indian context, the founding of Asiatic Society by Sir William Jones in 1784 provided an impetus for similar investigations into the history of India. The successful decipherment of Brahmi and Kharoshthi scripts in 1830s by James Princep, accelerated this study, as now the history of India is more understandable. The founding of Archaeological Survey of India (ASI) in 1861 after consistent persuasion of Alexander Cunningham started with an exploration of north Indian plains following the footsteps of Xuanchang, a Chinese pilgrim who had left a vast array of travellogues. Cunningham (1871, 1872), discovered ancient towns and cities, associated with the Buddhist religion and visited by Xuanchang, and also conducted exploratory diggings in many of them, for the purpose of retrieving relics and artefacts.
2. Beginnings of Archaeology and Discovery of Sites
Archaeology as a discipline did not emerge until the late 19th or early 20th century CE, and during the initial phases of 18th and early 19th century CE, it was marked by sensational discoveries of the like of Pompeii or Herculaneum and some sporadic diggings of vestiges of past here and there, mostly in private lands of wealthy landowners. During the early days, discovery of sculptures, art objects, paintings, treasures of gold and other valuable metals and stones, were highly unscientific in nature without any concept of understanding the chronology, history of a particular region or territory. Objects of historical and artistic interest were often collected and traded; some of them were displayed in private collections, which later grew into remarkable museums, like the Louvre Museum (France), British Museum (U.K.), Salarjung Museum (India). The most spectacular discoveries among the early days are the successful decipherment, albeit after enormous research, of the Hieroglyphs (1822) and Cuneiform (1850s) scripts belonging to Egyptian and Mesopotamian civilizations respectively, by Jean Francois Champollion and Henry Rawlinson. These decipherments were remarkable as they immediately helped in decipherment and interpret thousands of inscriptions that led to the better understanding of these civilizations. The use of ancient literature to identify a ‘lost’ city was successfully attempted by Heinrich Schliemann and Frank Calvert, the latter identifying Hissarlik (Turkey) with ancient Troy of Homer’s Iliad, and the former excavating it in 1871. Another example for a prolonged research and successful discovery of an ancient tomb is that of Tutankhamen by Howard Carter in 1922. Discoveries are still made by chance without the ‘modern’ framework of scientific archaeology. The best examples being the discovery of Terracotta Army in Shaanxi Province, China in 1974 and large Harappan Cemetery at Sanauli, Uttar Pradesh, India in 2005.
The role of archaeology as such for understanding of the remote past, particularly without written historical records, was better understood from some independent works of both scholars and enthusiasts. Renfrew and Bahn (2000) recall the excavation of Thomas Jefferson, carried out in 1784, as “the first scientific excavation in the history of archaeology”. The excavation by Jefferson, who became the third president of USA, was carried out in a burial mound in his property in Virginia. This particular excavation by Jefferson is cited as an example for ending the ‘speculative phase’ of archaeology, and to usher into an age of systematic interpretations, as the burial mounds proved to be ancestral cemetery of indigenous people, and not the mythical Moundbuilders (Renfrew and Bahn: 2000). The emergence of understanding on the antiquity of human past was an important development as it brought to an end several myths related to origin of human being. The idea of prehistory emerged with the discovery of stone tools from several parts of Europe, in particular of the discoveries made by Boucher de Perthes, who associated the relationship between the stone tools and faunal remains of extinct animals. The contribution of C.J. Thomson in understanding the human progression by differentiating the different technological stages of the past with the aid of tool typologies was also a major event in the history of archaeology. The ‘Three Age System’ developed by Thomson was so simple and convincing that even a lay person could understand the developments of the past, by differentiating different technological events like Age of Stone, Age of Bronze, Age of Iron, was proposed in his book titled A Guide to Northern Antiquities published in 1848 (Renfrew and Bahn 2000: 25). More or less during the same period, the concept of stratigraphy and uniformitarianism in the discipline of geology evolved and the pioneers in this aspect respectively were James Hutton (1785) and Charles Lyell (1833). The concept of stratigraphy in the geological perspective can be applicable in the archaeological deposits as well due to its universal application and nature. Archaeologists have refined the principles of stratigraphy incorporating more and more complex aspects of human depositional process, interventions and redepositions, which are very much different from the geological processes.
The development of field techniques in archaeology was a major step towards the understanding of human depositional processes for which the major contributors were Pitt Rivers (pioneer in recording techniques who adopted them in his excavation at Cranborne Chase), William Flinders Petrie (known for meticulous excavation and recording techniques in Egypt, and seriation or sequence dating), Mortimer Wheeler (extensive use of stratigraphy in excavation, grid-square method of excavation, mostly in India), Max Uhle (meticulous recording of graves and associated grave goods in South America), Alfred Kidder (involved specialists in analyzing artefacts). The approach of Kidder for understanding regional strategies as defined by Renfrew and Bahn (2000) is “(i) reconnaissance, (ii) selection of criteria for ranking the remains of sites chronologically, (iii) seriation into a probable sequence, (iv) stratigraphic excavation to elucidate specific problems, followed by (v) more detailed regional survey and dating”.
As mentioned above, in the Indian context, the impetus for archaeological investigations and research started with the efforts of Sir William Jones and it continued due to several individuals like James Princep, Sir Meadows Taylor, Sir Alexander Cunningham, Jas Burgess. The decipherment of Brahmi and Kharoshthi and their associated variants helped in better understanding of Indian history. The explorations were initially restricted to historical interest and places of historical value like places associated with Buddha and his life. During the course of these visits important protohistoric sites like Harappa (now in Pakistan) were being discovered. Individuals like Charles Masson and Alexander Burnes otherwise also visited the site of Harappa since 1829 CE onwards, in 1826 and 1933 respectively (Possehl 1999). Cunningham himself visited the site on three occasions, but he could not fully put the findings in proper perspective as search for archaeological sites associated with Buddhism was in much vogue and a chronology much earlier to Buddha could not be properly understood. The discovery of prehistoric and megalithic sites was being made by Harkens (Megaliths in Nilgiris, Tamil Nadu in1832), Primrose (Neolithic artefacts from Raichur Doab in1842) and Meadows Taylor (first systematic excavation of megaliths in north Karnataka in 1851). Robert Bruce Foote, in particular, carries the credit of the discovery of first palaeolith in Indian sub-continent at Pallavaram near Madras in 1863 (Korisettar 2002: 3). The other prominent figures who contributed extensively in discovering prehistoric sites are T.J. Newbold (Neolithic ashmounds), A.C.L. Carlyle (stone tools in Central India). Later, two international expeditions, first by L.A. Cammaide and M.C. Burkitt and second by de Terra and Paterson, led to understand the prehistoric remains systematically in the Indian sub-continent.
The excavation at Harappa from 1921 and at Mohenjo-daro from 1922 led to the discovery of Harappan Civilization in 1924. Simultaneously, several expeditions by Sir Aurel Stein in the Balochistan and Rajasthan areas along an extensive palaeochannel which also led to identification of several sites, which were now better understood after the identification of Harappan Civilization. Thus, enthusiasts and individuals mainly contributed during the initial phases of discoveries not from the discipline of archaeology, and later, the focus shifted on problem-oriented surveys to understand the human culture in a proper perspective.
3. Exploration or Reconnaissance
Archaeological exploration or reconnaissance precedes excavation of features and sites, as it is the basic tool to search and identify the remnants of any past human activity. From its initial days of only discovery of treasures and plundering artefacts, without caring for recording its context, exploration activities have witnessed tremendous transformation. With the development of archaeology as a multi-disciplinary science, more and more scientific methodologies are now in place along with traditional exploration techniques, right from the application of remote sensing on a much larger scale and area to site specific and localized techniques using geophysical tools. The archaeological sites are both discovered by systematic exploration on the ground and air through a problem-oriented survey as well as from accidental ones. One of the earliest examples of systematic ground renaissance in search of Harappan sites was undertaken by A. Ghosh of Archaeological Survey of India (ASI) along the dry bed of River Ghaggar (identified with River Sarasvati) in Rajasthan. This survey also led to similar explorations along the tributaries of River Ghaggar, one of which is River Chautang (identified with River Drishadvati), which again revealed many Harappan sites. Archaeological sites and artefacts are being discovered accidentally and by chance whenever any digging operation is conducted either for leveling purposes or agricultural activities. The discovery of one of the largest Harappan cemetery at Sanauli in Western Uttar Pradesh is a classic example in this regard (D.V. Sharma et al 2005), wherein leveling operations for agricultural purposes brought to light the skeletal remains along with typical late Harappan ceramics, copper sword, stone beads.
3.1 Locating archaeological sites using old maps and Google Earth
The first and foremost job of an archaeologist before proceeding on a fieldwork is to collect as much information as possible from old maps, literary sources, previous works, on a particular geographical area or zone in order to assess its potentiality for archaeological remains. In this regard, old maps are very much useful as they often provide a valid ground remains during the period in which it was prepared. It has been observed that even dried up rivers are marked prominently in these maps. A good example in this regard is a map published by Henry Beveridge (1867), which shows River Sarasvati (Soorsutty) and Ghaggar (Guggur) (Fig. 1). In this map, the river is shown just beyond Bhatneer (Bhatnair). Several early Harappan, Harappan sites are found along the course of this river, which is only visible during the rainy season now. The toposheets published by Survey of India are often good indicators of nature of villages and the remains they have. Often, the toposheets mention about ‘ruins’ or ‘deserted’, which may lead to identification of an archaeological site. One such example is from a map compiled from Survey of India 1” maps wherein one of the five largest Harappan sites, Dholavira, is mentioned as ‘Kotada (Deserted)’. Similarly, several other localities in the same map has been marked with ‘deserted’, which may lead to discovery of new sites, as the entire Khadir island on which Dholavira is located is strewn with host of sites.
The 1” (1:25,000) toposheet of the Survey of India is an excellent documentary evidence for locating ruins, old forts, temples, and other historical places. These toposheets faithfully document all such structures and remains of historical importance, which are very much helpful in understanding the antiquity of villages, towns and cities. These maps are also useful in planning an exploratory survey so that several factors like distance, elevation, topography, river courses, oxbow lakes, lakes and water reservoirs, that can be easily delineated and used for reconnaissance for archaeological remains.
The Google Earth application, which is free as well as paid software, is another source in which the terrain and geography can be easily understood. Further, the palaeochannels, abandoned channels of rivers as well as dry bed of rivers can be easily delineated from the surrounding areas, which can be a potential source for exploration of ancient sites. Another important feature of Google Earth is to create geotagged location files in the kml or kmz format, which can be easily imported in GIS software for mapping purposes. Through this procedure, not only the location of sites can be plotted, features like lakes, rivers, and any polygon can be created and exported into GIS software for visual representation and interpretation.
3.2 Locating archaeological sites using ancient literature and travelogue
Often, looking into the references from ancient literature and travelogue provides very good evidence of location of archaeological sites. The plethora of ancient literature of South Asia is one among the oldest in the world and it is widely accepted that the earliest Sanskrit literature dates back to at least 4000 years, even on a conservative estimate. The historical and geographical information provided in this literature often provides clues of ancient habitation in a particular geographical zone or area. For example, the Rig Veda provides ample evidence of the Sindhu (Indus River) along with its tributaries like Drishadvati, Sarasvati, Sutudri (Satluj), Vipasa (Beas), Parushni (Ravi), Asikni (Chenab), Vitasta (Jhelum), Suvastu (Swat), Kubha (Kabul), Gomati (Gomal), which defines its geography. The Epics like Ramayana and Mahabharata mentions a host of cites and towns, which, on investigations under a project named Archaeology of Ramayana and Mahabhara Sites, revealed its history to at least 3000 years from some sites. The ancient travelogues are also valuable sources of locations of ancient port towns, capital cities and kingdoms. The unknown author of Periplus Maris Erithraei faithfully records the port towns, costal conditions and interior kingdoms during the first century CE, along with important exports from respective locations. This literature along with other classical Roman writers provides location of port towns on the western and eastern coast of India, famous among them being Barygaza (Bharuch), Muziris (Pattanam), Colchi (Korkai), Argaru (Uraiyur), Kaberis Emporion (Kaveripumpattinam), Poduke (Arikamedu), Mylarpha (Mylapore), to name a few.
The excavation at locations like Pattinam, Arikamedu have yielded excellent remains of artefacts like gold coins of Roman rulers, gold jewellery, cameos, intaglios, pottery like amphora, terra sigillata and Roman glass from the Mediterranean region, particularly from 1 c. BCE to 2nd c. CE, indicating a brisk trade between these two regions. The survey carried out by Alexander Cunningham based on the travelogue of Xuanzang, Chinese traveller, during 1861 – 1878 helped in locating a majority of the cities and historical places visited by the traveller in 7th c. CE. Cunningham, based on the ground survey was successful in locating several important cities like Sankissa, Ahichchhatra, Sravasti, to name a few.
Thus, reviewing and researching through the historical and ancient literature along with travelogue can be an excellent source for locating ancient sites.
3.3 Locating archaeological sites through remote sensing surveys
The exploration and reconnaissance of vast geographical areas is not possible in a short time period. In this regard, remote sensing surveys can be helpful in having a preliminary understanding of the terrain and nature of sites. The remote sensing surveys can be either simple in the form of aerial photographs taken from aircrafts to hot air balloons to complex satellite images using various sensors. The concept and examples of various remote-sensing techniques will be introduced in the module on Scientific Tools in Archaeological Exploration.
3.4 Locating archaeological sites through ground surveys
Even though map reading, remote sensing, researching through ancient literature and travelogue give a preliminary idea of archaeological remains and sites, without carrying out a ground survey, no site can be located and identified. Exploration of a terrain and landscape with a well-conceived framework of research into the human past is the most simplest and inexpensive mode for conducting archaeological research. Exploration, even though time consuming, is a better option and less destructive, rather to conduct excavation of a host of sites. Any systematic exploration methodology for locating and pinpointing archaeological sites and artefacts is incomplete without a well-planned ground survey. If the aerial or remote sensing surveys give a broader perspective of archaeological sites, it is the ground survey alone, which confirms the conclusions drawn from such surveys. The traditional approaches for archaeological explorations consist of village-to-village surveys or district surveys looking for ‘material remains’ of bygone ages and to reconstruct a plausible cultural-historical model. The concept of surveying entire landscapes, which also enabled to identify agricultural land use, lynchets (parallel heaps of stones marking boundary of fields), buried tracks, road and buildings was an important feature of European survey methodology (Banning 2002). The use of suitable sampling strategies to survey an entire landscape and statistical methods is an important aspect in any such exploration. In this regard, probabilistic survey methods consisting of simple random, stratified random, systematic and stratified unaligned systematic surveys, are available and the most suitable one can be adopted depending upon the nature of the landscape and terrain (Renfrew & Bahn: 2000).
3.4.1 Types of Surveys
Renfrew & Bahn (2000) succinctly summarises the various types of surveys that are employed in systematic ground exploration for better results along with examples. The surveys are based on statistical methods and employ probability theory for better results, and are also called probabilistic sampling. A non-statistical methodology can also be employed, which is known as non-probabilistic sampling, which is necessitated due to several ground realities, nature of the terrain to be surveyed, accessibility, experience of the investigator, which may not warrant a probabilistic sampling. However, a systematic sampling strategy will always supplement and help in obtaining more scientific results.
The probabilistic survey techniques consist of (i) simple random sampling, (ii) stratified random sampling, (iii) systematic sampling, and (iv) stratified unaligned systematic sampling
3.4.1.1 Simple Random Sampling
In this method, the area or landscape to be surveyed is defined first, which is also known as site universe, its boundaries defined, followed by defining the size of grid or square that is to be used for surveying within the defined boundaries. This is followed by a decision regarding the number of grids of defined size to be surveyed within the overall area. This number is decided randomly, from a grid of squares defined for the survey area or landscape. In order to obtain a better and useful outcome of the survey, large sample size, or survey in large number of squares or grids, is necessary. The drawbacks of this method are (i) area to be surveyed defined beforehand, which may be a shortcoming, as the actual survey may indicate the spread of cultural remains outside the defined boundaries, (ii) the selection of grids or squares from random table, may result in clustering and several areas may be omitted, which results in biased sampling.
3.4.1.2 Stratified Random Sampling
In this method, the survey area is defined as per the geographical and natural features, e.g. forested area, plains, and others, followed by calculating the percentage of such areas in the overall survey area. The gridding is then done based on the same simple random sampling, the only difference being the percentage of grids to be surveyed depends upon the percentage of individual natural features from within the overall area.
3.4.1.3 Systematic Sampling
In this method, the distance between the grids / squares to be surveyed is kept a constant or regular spacing. The drawback of this system is that there is an incremental possibility of missing potential squares.
3.4.1.4 Stratified Unaligned Systematic Sampling
In this method, elements from all the above techniques are used as per the requirement, broadly removing the drawbacks within each technique. For example, defining the boundary in Simple Random Sampling can be discarded and the survey area may be extended in any desired direction as per the ground realities. Further, the axis of grids can also be decided as per the orientation of surface features of large archaeological mounds. For example, the Harappan sites are oriented either towards the west or east of True North. The axes of surveying grids can be defined looking into the ground features of such sites for better understanding the overall features.
3.4.1.5 Linear Surveys of Transects
This method of surveying long linear transects is particularly useful for large landscapes, which may extend to several sq. km. Renfrew & Bahn (2000) opines that transects are particularly useful in areas with dense vegetation, as following a path is often more easy when compared to the survey of defined grids. The transects are also linear surveys following a path, unless the width is defined, and hence a small area to be surveyed when compared to grids. It is, therefore, observed that a combination of transects and squares can be a good technique for ground surveys. Often, the transects are carried out in groups of 4 to 5 archaeologists traversing a terrain in a given path, thereby surveying a considerable width, which leads to less discrepancy.
3.5 Examples of Ground Surveys, Linear Surveys and Transects
The focus on more and more systematic and integrated site surveys is now the norm which has helped in retrieving artefacts and information pertaining to settlement pattern, raw material distribution, industrial activities, to name a few. Several examples can be quoted in this regard, wherein minimalistic intervention in the form of exploratory surveys followed by sample collections was made and to a large extent excavations were avoided. One such example is the project entitled, “Herder’s Monuments: Ashmounds of Southern Deccan Neolithic” (Rajala et al 2004). A more regional approach was adopted in this project to understand the periodic cycles of activities of Neolithic ashmounds in Southern India, particularly in Karnataka (Bellary, Raichur and Gulbarga districts) and Andhra Pradesh (now Telangana, Anantapur district). Even though the research on the ashmounds is well over hundred years, a complete understanding is still lacking. The objectives of this project were to have a geoarchaeological and phytolith perspectives to understand the cyclic events, understand the nature of the ashmounds in terms of ritualism and/or symbolism, the human settlements associated with them and to record and collect as much information as they are endangered due to various developmental activities, agricultural expansion and vagaries of nature. The project envisaged a Systematic Integrated Data Collection on ashmounds through (i) collating information arriving from the fieldwork, which involved in documenting each ashmound, drawing site plans, gridded systematic survey transects of endangered sites; (ii) computational strategy involving integration of available cartographic, digital maps and satellite imageries to evolve a digital cartography, photographic archive and GIS platform for landscape analysis and visualization. Some of the most important sites like Sanganakallu were surveyed in detail using Total Station to document the present condition of the site and to preserve it in a digital format. This survey was the first of its kind, which helped in developing a GIS based interpretive tool for the ashmounds of South India.
The Sanchi Survey Project by Julia Shaw aimed in understanding the Buddhist monastic settlement of Sanchi in terms of spread of religion, urbanization, state formation, economic change, agricultural activities, networks for trade and communication (Shaw 2005). The survey methodology consisted of exploring an area of 750 sq. km. around the monastic complex at Sanchi (Shaw 2015). The methodology of the survey consisted of intensive exploration of the defined area, collection of sediments from dams and reservoirs, mapping and systematic remote sensing (Shaw 2005). The survey led to the recording of “35 Buddhist sites, 145 settlements, 17 irrigation dams, and over 1000 sculptural and architectural fragments associated with Hinduism, Jainism and local cults” (Shaw 2005). The investigations helped in understanding the role of Buddhism in establishing agricultural and water management practices during second century BCE, thereby contributing to the agrarian and economic base of the contemporary society.
The Anuradhapura (Sri Lanka) Project by Robin Coningham et al (2006) is an excellent example of surface survey methodology. As Coningham et al (2006) points out, the traditional approach of investigation is more concentrated on the specific site itself without taking into consideration on the role of immediate and distant precincts. The methodology consisted of an intensive survey of an area having 50 km radius with Anuradhapura at its centre, to document and map location of non-urban sites, and collection of samples for analysis. The survey methodology consist of random transect lines of about 10 km crisscrossing this area covering all aspects like “rocky outcrops and ridges, streams and rivers, grasslands, forests, tanks, villages, chena (swidden agriculture) and paddyfields” (Coningham et al 2006). The recording methodology involved 10 archaeologists in a team walking in this transect and recording various features like “topography, vegetation, land use, resources and cultural features” (Coningham et al 2006). The recording of cultural features, indicated by artefacts, ceramics or lithics were documented, sketched and location marked by GPS, while samples, sediments were collected for analysis. The survey was also extended outside the defined transect to explore the nearby river (Malwatu Oya) to understand the nature of settlements along the banks and also identifying points of transport as this river connected the city to the coastal area. The survey helped in identifying various categories of sites like ceramic scatters, monastic, stone pillars and walls, metal-working areas, conical holes on rock outcrops, megalithic burials, stone bridges and annicuts and modern sites.
- Summary
From the ongoing discussion, it has been observed that exploration or reconnaissance is definitely a low cost operation when compared to excavation, and it can yield results from large landscapes to understand an overall picture of the given area. The technique of locating archaeological sites is multifaceted, starting from simple map reading to getting help from Google Earth images, to follow the ancient literature and travelogue, followed by intensive surface survey following different methods. It is always a combination of several techniques, which leads to the discovery of several archaeological features, if not large in size and not under occupation for considerable period. There are examples of important sites discovered by chance due to developmental activities, which are subjected to more intensive investigations depending upon the potentiality of findings. The exploration of large areas is followed by intensive survey of potential areas and individual sites and features. The sampling strategies for individual sites and features also follow the same probabilistic sampling methodologies which precede the actual excavation, as the latter is time consuming and very slow in nature.
Web links
- http://www.ucl.ac.uk/archaeology/research/directory/sanchi_shaw
- https://www.dur.ac.uk/archaeology/research/projects/all/?mode=project&id=251
- https://www.dur.ac.uk/archaeology/research/projects/all/?mode=project&id=252