Remote sensing (archaeology)
Encyclopedia
Remote sensing techniques in archaeology are an increasingly important component of the technical and methodological tool set available in archaeological
research.. The use of remote sensing
techniques allows archaeologists to uncover unique data that is unobtainable using traditional archaeological excavation techniques. 'Remote sensing' is sometimes used to refer to ground-based geophysical surveys, but these are considered a separate discipline.
Ground-based geophysical methods such as Ground Penetrating Radar
and Magnetometry
are also used for archaeological imaging. Although these are sometimes classed as remote sensing, they are usually considered a separate discipline (see Geophysical survey (archaeology)).
studies in Mesoamerica
. The Petén
region of northern Guatemala
is of particular focus because remote sensing
technology is of very definite use there. The Petén is a densely forested region and it lacks modern settlements and infrastructure. As a result, it is extremely difficult to survey, and because of this remote sensing offers a solution to this research problem. The use of remote sensing techniques in this region is a great example of the applications these methods have for archaeologists. The Petén is a hilly, karst
ic, thickly forested landscape which offers an incredible barrier for field archaeologists to penetrate. With the advent of remote sensing techniques, a plethora of information has been uncovered about the region and about the people that inhabited it.
The Petén is arguably one of the most difficult of the Maya landscapes in which to subsist. It is questions regarding subsistence patterns and related problems that have driven remote sensing methodology in the hopes of understanding the complex adaptations that the Maya developed. Remote sensing methods have also proven invaluable when working to discover features
, cisterns, and temples. Archaeologists have identified vegetative differentiation associated with such features. With the advent of remote sensing, archaeologists are able to pinpoint and study the features hidden beneath this canopy without ever visiting the jungle.
A pioneer in the use of remote sensing in Maya research is NASA
archaeologist Tom Sever, who has applied remote sensing to research in Maya site discovery as well as mapping causeways (sacbe
ob) and roads. Sever has stressed the enormous use of remote sensing in uncovering settlement patterns, population densities, societal structure, communication, and transportation . Sever has done much of his research in the Petén region of northern Guatemala, where he and his research team have used satellite imagery and GIS to map undiscovered roads and causeways the ancient Maya
built to connect cities and settlements. These landscape artifacts represent the advantage of using remote sensing
as these causeways are not visible from the ground. By mapping these forms, Sever is able to locate new sites and further uncover ancient Maya methods of communicated and transportation. Sever and his team also use remote sensing methods to gather data on deforestation
. The rain forests of the Petén are undergoing massive deforestation, and Sever's remote sensing offers another window into this understanding and halting this problem. Monitoring the rate of deforestation not only has important ecological value, but the use of remote sensing can detect landscape change. By measuring the magnitude of landscape change in terms of vegetative cover and soil geography, as well as shifting land use patterns and the associated cultural diversity, archaeologists are given a window into depletion rates and trends in anthropogenic landscape alteration.
Much attention has been devoted to the mapping of canals and irrigation
systems . Synthetic Aperture Radar (SAR) has proved particularly useful in this research. SAR is a type of radar that is sensitive to linear and geometric features on the ground . It is also important include a method called ground truth
ing, or the process of physically visiting (on foot) the localities surveyed to verify the data and help inform the interpretation. GPS is often used to aid in this process.
Ground-based geophysical methods have also been employed in Maya research. Ground Penetrating Radar
(GPR) has been performed on a number of sites, including Chichen Itza
. The GPR research has detected buried causeways and structures that might have otherwise gone unnoticed .
, a happenstance often referred to as the "(Classic) Maya collapse
". Sever's research on communication and transportation systems points to an extensive societal infrastructure capable of supporting the building and maintenance of the causeways and roadways. Using satellite imagery
, researchers have been able to map canals and reservoirs. These offer a glimpse into Maya cultural adaptations during the period of their highest population density. At the height of the classic period, the population in the Maya lowlands was 500 - 1300 people per square mile in rural areas, and even more in urban regions. This far outweighs the carrying capacity for this region, but this follows centuries of successful adaptation. Other data shows that by the end of the classic period, the Maya had already depleted much of the rain forest. Understanding how the ancient Maya adapted to this karst
topography could shed light on solutions to modern ecological problems that modern peoples in the Petén currently face, which is much the same, except there are fewer people who are causing even more damage to the biodiversity and cultural diversity . Sever believes that the Maya collapse was a primarily ecological disaster. By detecting deforestation rates and trends can help us to understand how these same processes affected the Maya.
(or region surrounding the lost city) on the Arabian Peninsula
. In the early 1980s a group of researchers interested in the history of Iram used NASA
remote sensing satellites, ground penetrating radar, Landsat program
data and images taken from the Space Shuttle Challenger
as well as SPOT
data to identify old camel train
routes and points where they converged. These roads were used as frankincense
trade routes around 2800 BC to 100 BC.
One area in the Dhofar
province of Oman
was identified as a possible location for an outpost of the lost civilization. A team including adventurer Ranulph Fiennes
, archaeologist Juris Zarins
, filmmaker Nicholas Clapp
, and lawyer George Hedges
, scouted the area on several trips, and stopped at a water well called Ash Shisar. Near this oasis was located a site previously identified as the 16th century Shis'r fort. Excavations uncovered an older settlement, and artifacts traded from far and wide were found. This older fort was found to have been built on top of a large limestone cavern which would have served as the water source for the fort, making it an important oasis on the trade route to Iram. As the residents of the fort consumed the water from underground, the water table fell, leaving the limestone roof and walls of the cavern dry. Without the support of the water, the cavern would have been in danger of collapse, and it seems to have done so some time between 300-500 AD, destroying the oasis and covering over the water source.
Four subsequent excavations were conducted by Dr. Juris Zarins
, tracing the historical presence by the people of 'Ad, the assumed ancestral builders of Iram.
Archaeology
Archaeology, or archeology , is the study of human society, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes...
research.. The use of remote sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...
techniques allows archaeologists to uncover unique data that is unobtainable using traditional archaeological excavation techniques. 'Remote sensing' is sometimes used to refer to ground-based geophysical surveys, but these are considered a separate discipline.
General techniques
Remote Sensing methods employed in the service of archaeological investigations include:- Aerial and Satellite Imaging
- Aerial photographyAerial photographyAerial photography is the taking of photographs of the ground from an elevated position. The term usually refers to images in which the camera is not supported by a ground-based structure. Cameras may be hand held or mounted, and photographs may be taken by a photographer, triggered remotely or...
- MultispectralMultispectral ScannerThe Multispectral Scanner is one of the Earth observing sensors introduced in the Landsat program. A Multispectral Scanner was placed aboard each of the first five Landsat satellites.-MSS Technical Specifications:...
and Hyperspectral SensorsHyperspectral imagingHyperspectral imaging collects and processes information from across the electromagnetic spectrum. Much as the human eye sees visible light in three bands , spectral imaging divides the spectrum into many more bands... - Thermal Infrared Multispectral Scanner (TIMS)Multispectral ScannerThe Multispectral Scanner is one of the Earth observing sensors introduced in the Landsat program. A Multispectral Scanner was placed aboard each of the first five Landsat satellites.-MSS Technical Specifications:...
- Color Infrared Film (CIR)Infrared photographyIn infrared photography, the film or image sensor used is sensitive to infrared light. The part of the spectrum used is referred to as near-infrared to distinguish it from far-infrared, which is the domain of thermal imaging. Wavelengths used for photography range from about 700 nm to about...
- Microwave RadarRadarRadar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
- Multispectral
- Satellite Imaging
- Laser altimeters or light detection and ranging (LIDAR)LIDARLIDAR is an optical remote sensing technology that can measure the distance to, or other properties of a target by illuminating the target with light, often using pulses from a laser...
- Synthetic Aperture Radar (SAR)Synthetic aperture radarSynthetic-aperture radar is a form of radar whose defining characteristic is its use of relative motion between an antenna and its target region to provide distinctive long-term coherent-signal variations that are exploited to obtain finer spatial resolution than is possible with conventional...
- INSAR - Interferometric SARInterferometric synthetic aperture radarInterferometric synthetic aperture radar, also abbreviated InSAR or IfSAR, is a radar technique used in geodesy and remote sensing. This geodetic method uses two or more synthetic aperture radar images to generate maps of surface deformation or digital elevation, using differences in the phase of...
- Laser altimeters or light detection and ranging (LIDAR)
- Aerial photography
Ground-based geophysical methods such as Ground Penetrating Radar
Ground-penetrating radar
Ground-penetrating radar is a geophysical method that uses radar pulses to image the subsurface. This nondestructive method uses electromagnetic radiation in the microwave band of the radio spectrum, and detects the reflected signals from subsurface structures...
and Magnetometry
Magnetometer
A magnetometer is a measuring instrument used to measure the strength or direction of a magnetic field either produced in the laboratory or existing in nature...
are also used for archaeological imaging. Although these are sometimes classed as remote sensing, they are usually considered a separate discipline (see Geophysical survey (archaeology)).
Maya research
Some of the most prominent remote sensing research has been done in regard to MayaMaya civilization
The Maya is a Mesoamerican civilization, noted for the only known fully developed written language of the pre-Columbian Americas, as well as for its art, architecture, and mathematical and astronomical systems. Initially established during the Pre-Classic period The Maya is a Mesoamerican...
studies in Mesoamerica
Mesoamerica
Mesoamerica is a region and culture area in the Americas, extending approximately from central Mexico to Belize, Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica, within which a number of pre-Columbian societies flourished before the Spanish colonization of the Americas in the 15th and...
. The Petén
Petén Basin
The Petén Basin is a geographical subregion of Mesoamerica, located in the northern portion of the modern-day nation of Guatemala, and essentially contained within the department of El Petén...
region of northern Guatemala
Guatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...
is of particular focus because remote sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...
technology is of very definite use there. The Petén is a densely forested region and it lacks modern settlements and infrastructure. As a result, it is extremely difficult to survey, and because of this remote sensing offers a solution to this research problem. The use of remote sensing techniques in this region is a great example of the applications these methods have for archaeologists. The Petén is a hilly, karst
KARST
Kilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...
ic, thickly forested landscape which offers an incredible barrier for field archaeologists to penetrate. With the advent of remote sensing techniques, a plethora of information has been uncovered about the region and about the people that inhabited it.
The Petén is arguably one of the most difficult of the Maya landscapes in which to subsist. It is questions regarding subsistence patterns and related problems that have driven remote sensing methodology in the hopes of understanding the complex adaptations that the Maya developed. Remote sensing methods have also proven invaluable when working to discover features
Feature (archaeology)
Feature in archaeology and especially excavation has several different but allied meanings. A feature is a collection of one or more contexts representing some human non-portable activity that generally has a vertical characteristic to it in relation to site stratigraphy. Examples of features are...
, cisterns, and temples. Archaeologists have identified vegetative differentiation associated with such features. With the advent of remote sensing, archaeologists are able to pinpoint and study the features hidden beneath this canopy without ever visiting the jungle.
A pioneer in the use of remote sensing in Maya research is NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
archaeologist Tom Sever, who has applied remote sensing to research in Maya site discovery as well as mapping causeways (sacbe
Sacbe
right|thumb|Sacbe at Dzibilchaltun in the Yucatánthumb|right|Arch at the end of the sacbé, Kabah, YucatánSacbe, plural Sacbeob, or "white ways" are raised paved roads built by the Maya civilization of pre-Columbian Mesoamerica...
ob) and roads. Sever has stressed the enormous use of remote sensing in uncovering settlement patterns, population densities, societal structure, communication, and transportation . Sever has done much of his research in the Petén region of northern Guatemala, where he and his research team have used satellite imagery and GIS to map undiscovered roads and causeways the ancient Maya
Maya civilization
The Maya is a Mesoamerican civilization, noted for the only known fully developed written language of the pre-Columbian Americas, as well as for its art, architecture, and mathematical and astronomical systems. Initially established during the Pre-Classic period The Maya is a Mesoamerican...
built to connect cities and settlements. These landscape artifacts represent the advantage of using remote sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...
as these causeways are not visible from the ground. By mapping these forms, Sever is able to locate new sites and further uncover ancient Maya methods of communicated and transportation. Sever and his team also use remote sensing methods to gather data on deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
. The rain forests of the Petén are undergoing massive deforestation, and Sever's remote sensing offers another window into this understanding and halting this problem. Monitoring the rate of deforestation not only has important ecological value, but the use of remote sensing can detect landscape change. By measuring the magnitude of landscape change in terms of vegetative cover and soil geography, as well as shifting land use patterns and the associated cultural diversity, archaeologists are given a window into depletion rates and trends in anthropogenic landscape alteration.
Much attention has been devoted to the mapping of canals and irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...
systems . Synthetic Aperture Radar (SAR) has proved particularly useful in this research. SAR is a type of radar that is sensitive to linear and geometric features on the ground . It is also important include a method called ground truth
Ground truth
Ground truth is a term used in cartography, meteorology, analysis of aerial photographs, satellite imagery and a range of other remote sensing techniques in which data are gathered at a distance. Ground truth refers to information that is collected "on location." In remote sensing, this is...
ing, or the process of physically visiting (on foot) the localities surveyed to verify the data and help inform the interpretation. GPS is often used to aid in this process.
Ground-based geophysical methods have also been employed in Maya research. Ground Penetrating Radar
Ground-penetrating radar
Ground-penetrating radar is a geophysical method that uses radar pulses to image the subsurface. This nondestructive method uses electromagnetic radiation in the microwave band of the radio spectrum, and detects the reflected signals from subsurface structures...
(GPR) has been performed on a number of sites, including Chichen Itza
Chichen Itza
Chichen Itza is a large pre-Columbian archaeological site built by the Maya civilization located in the northern center of the Yucatán Peninsula, in the Municipality of Tinúm, Yucatán state, present-day Mexico....
. The GPR research has detected buried causeways and structures that might have otherwise gone unnoticed .
Maya "collapse"
One of Sever's research goals is understanding the comparatively sudden decline of many Maya centers in the central Lowlands region by the end of the 1st millennium CECommon Era
Common Era ,abbreviated as CE, is an alternative designation for the calendar era originally introduced by Dionysius Exiguus in the 6th century, traditionally identified with Anno Domini .Dates before the year 1 CE are indicated by the usage of BCE, short for Before the Common Era Common Era...
, a happenstance often referred to as the "(Classic) Maya collapse
Classic Maya collapse
The Classic Maya Collapse refers to the decline and abandonment of the Classic Period Maya cities of the southern Maya lowlands of Mesoamerica between the 8th and 9th centuries. This should not be confused with the collapse of the Preclassic Maya in the 2nd century AD...
". Sever's research on communication and transportation systems points to an extensive societal infrastructure capable of supporting the building and maintenance of the causeways and roadways. Using satellite imagery
Satellite imagery
Satellite imagery consists of photographs of Earth or other planets made by means of artificial satellites.- History :The first images from space were taken on sub-orbital flights. The U.S-launched V-2 flight on October 24, 1946 took one image every 1.5 seconds...
, researchers have been able to map canals and reservoirs. These offer a glimpse into Maya cultural adaptations during the period of their highest population density. At the height of the classic period, the population in the Maya lowlands was 500 - 1300 people per square mile in rural areas, and even more in urban regions. This far outweighs the carrying capacity for this region, but this follows centuries of successful adaptation. Other data shows that by the end of the classic period, the Maya had already depleted much of the rain forest. Understanding how the ancient Maya adapted to this karst
KARST
Kilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...
topography could shed light on solutions to modern ecological problems that modern peoples in the Petén currently face, which is much the same, except there are fewer people who are causing even more damage to the biodiversity and cultural diversity . Sever believes that the Maya collapse was a primarily ecological disaster. By detecting deforestation rates and trends can help us to understand how these same processes affected the Maya.
Location of ancient Iram
Iram of the Pillars is a lost cityLost city
A "Lost City" is a term that is generally considered to refer to a well-populated area which fell into terminal decline, became extensively or completely uninhabited, and whose location has been forgotten. Some lost cities whose locations have been rediscovered have been studied extensively by...
(or region surrounding the lost city) on the Arabian Peninsula
Arabian Peninsula
The Arabian Peninsula is a land mass situated north-east of Africa. Also known as Arabia or the Arabian subcontinent, it is the world's largest peninsula and covers 3,237,500 km2...
. In the early 1980s a group of researchers interested in the history of Iram used NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
remote sensing satellites, ground penetrating radar, Landsat program
Landsat program
The Landsat program is the longest running enterprise for acquisition of satellite imagery of Earth. On July 26, 1972 the Earth Resources Technology Satellite was launched. This was eventually renamed to Landsat. The most recent, Landsat 7, was launched on April 15, 1999. The instruments on the...
data and images taken from the Space Shuttle Challenger
Space Shuttle Challenger
Space Shuttle Challenger was NASA's second Space Shuttle orbiter to be put into service, Columbia having been the first. The shuttle was built by Rockwell International's Space Transportation Systems Division in Downey, California...
as well as SPOT
SPOT (satellites)
SPOT is a high-resolution, optical imaging Earth observation satellite system operating from space. It is run by Spot Image based in Toulouse, France...
data to identify old camel train
Camel train
A camel train is a series of camels carrying goods or passengers in a group as part of a regular or semi-regular service between two points. Although they rarely travelled faster than the walking speed of a man, camels' ability to handle harsh conditions made camel trains a vital part of...
routes and points where they converged. These roads were used as frankincense
Frankincense
Frankincense, also called olibanum , is an aromatic resin obtained from trees of the genus Boswellia, particularly Boswellia sacra, B. carteri, B. thurifera, B. frereana, and B. bhaw-dajiana...
trade routes around 2800 BC to 100 BC.
One area in the Dhofar
Dhofar
The Dhofar region lies in Southern Oman, on the eastern border with Yemen. Its mountainous area covers and has a population of 215,960 as of the 2003 census. The largest town in the region is Salalah. Historically, it was the chief source of frankincense in the world. However, its frankincense...
province of Oman
Oman
Oman , officially called the Sultanate of Oman , is an Arab state in southwest Asia on the southeast coast of the Arabian Peninsula. It is bordered by the United Arab Emirates to the northwest, Saudi Arabia to the west, and Yemen to the southwest. The coast is formed by the Arabian Sea on the...
was identified as a possible location for an outpost of the lost civilization. A team including adventurer Ranulph Fiennes
Ranulph Fiennes
Sir Ranulph Twisleton-Wykeham-Fiennes, 3rd Baronet, OBE , better known as Ranulph Fiennes, is a British adventurer and holder of several endurance records. He is also a prolific writer. Fiennes served in the British Army for eight years including a period on counter-insurgency service while...
, archaeologist Juris Zarins
Juris Zarins
Juris Zarins is an American-Latvian archaeologist and professor at Missouri State University, who specializes in the Middle East....
, filmmaker Nicholas Clapp
Nicholas Clapp
Nicholas Clapp is a Borrego Springs, California based writer, film-maker, and amateur archaeologist. He has often been called the "real Indiana Jones" and he has received 70 film awards and several Academy Award nominations. He has two daughters, Jennifer and Cristina...
, and lawyer George Hedges
George Hedges
George Reynolds Hedges was a lawyer with a list of celebrity clients including Mel Gibson and David Lynch who gained attention in the field of archeology for his discovery of the ancient city of Ubar.-Biography:...
, scouted the area on several trips, and stopped at a water well called Ash Shisar. Near this oasis was located a site previously identified as the 16th century Shis'r fort. Excavations uncovered an older settlement, and artifacts traded from far and wide were found. This older fort was found to have been built on top of a large limestone cavern which would have served as the water source for the fort, making it an important oasis on the trade route to Iram. As the residents of the fort consumed the water from underground, the water table fell, leaving the limestone roof and walls of the cavern dry. Without the support of the water, the cavern would have been in danger of collapse, and it seems to have done so some time between 300-500 AD, destroying the oasis and covering over the water source.
Four subsequent excavations were conducted by Dr. Juris Zarins
Juris Zarins
Juris Zarins is an American-Latvian archaeologist and professor at Missouri State University, who specializes in the Middle East....
, tracing the historical presence by the people of 'Ad, the assumed ancestral builders of Iram.