Wednesday, January 12, 2011
absolute location–exact location of a place on
the earth described by global coordinates
basin–area of land drained by a given river and
its branches; area of land surrounded by lands
of higher elevations
bay–part of a large body of water that extends
into a shoreline
canyon–deep and narrow valley with steep walls
cape–point of land surrounded by a body of
channel–deep, narrow body of water that connects
two larger bodies of water; deep part of
a river or other waterway
cliff–steep, high wall of rock, earth, or ice
continent–one of the seven large landmasses on
cultural feature–characteristic that humans have
created in a place, such as language, religion,
delta–land built up from soil carried downstream
by a river and deposited at its mouth
divide–stretch of high land that separates river
downstream–direction in which a river or stream
flows from its source to its mouth
elevation–height of land above sea level
Equator–imaginary line that runs around the
earth halfway between the North and South
Poles; used as the starting point to measure
degrees of north and south latitude
glacier–large, thick body of slowly moving ice,
found in mountains and polar regions
globe–sphere-shaped model of the earth
gulf–part of a large body of water that extends
into a shoreline, larger than a bay
harbor–a sheltered place along a shoreline where
ships can anchor safely
highland–elevated land area with sloping sides
such as a hill, mountain, or plateau, smaller
than a mountain
island–land area, smaller than a continent, completely
surrounded by water
isthmus–narrow stretch of land connecting two
larger land areas
lake–a sizable inland body of water
latitude–distance north or south of the Equator,
measured in degrees
longitude–distance east or west of the Prime
Meridian, measured in degrees
lowland–land, usually level, at a low elevation
map–drawing of all or part of the earth shown
on a flat surface
meridian–one of many lines on the global grid
running from the North Pole to the South
Pole, used to measure degrees of
mesa–area of raised land with steep sides; smaller
than a plateau
mountain–land with steep sides that rises
sharply from surrounding land; larger and
more rugged than a hill
mountain peak–pointed top of a mountain
mountain range–a series of connected
mouth–(of a river) place where a stream or river
flows into a larger body of water
ocean–one of the four major bodies of salt water
that surrounds a continent
ocean current–stream of either cold or warm
water that moves in a definite direction
through an ocean
parallel–one of many lines on the global grid
that circle the earth north or south of the
Equator; used to measure degrees of latitude
peninsula–body of land almost surrounded by
physical feature–characteristic of a place occurring
naturally, such as a landform, body of
water, climate pattern, or resource
plain–area of level land, usually at a low
plateau–area of flat or rolling land at a high
Prime Meridian–line of the global grid running
from the North Pole to the South Pole at
Greenwich, England; used as the starting
point for measuring degrees of east and west
relative location–position of a place on the earth
in relation to other places
relief–changes in elevation, either few or many,
that occur over a given area of land
river–large stream of water that runs through the
sea–large body of water completely or partly
surrounded by land
seacoast–land lying next to a sea or ocean
sea level–average level of an ocean’s surface
sound–body of water between a shoreline and
one or more islands off the coast
source–(of a river) place where a river or stream
begins, often in high lands
strait–narrow stretch of water joining two larger
bodies of water
tributary–small river or stream that flows
into a large river or stream; a branch of the
upstream–direction opposite the flow of a river;
toward the source of a river or stream
valley–area of low land between hills or
volcano–mountain created as liquid rock or ash
are thrown up from inside the earth
Modern scientific techniques help scientists measure the age of ancient rocks such as these pegmatite with quartz and feldspar ones in Wyoming’s Teton Range. Dr. Marli Miller/Visuals Unlimited/Getty Images
Geochronology is the field of scientific investigation concerned with determining the age and history of the Earth’s rocks and rock assemblages. Such time determinations are made and the record of past geologic events is deciphered by studying the distribution and succession of rock strata, as well as the character of the fossil organisms preserved within the strata.
The Earth’s surface is a complex mosaic of exposures of different rock types that are assembled in an astonishing array of geometries and sequences. Individual rocks in the myriad of rock outcroppings (or in some instances shallow subsurface occurrences) contain certain materials or mineralogic information that can provide insight as to their “age.”
For years investigators determined the relative ages of sedimentary rock strata on the basis of their positions in an outcrop and their fossil content. According to a longstanding principle of the geosciences, that of superposition, the oldest layer within a sequence of strata is at the base and the layers are progressively younger with ascending order. The relative ages of the rock strata deduced in this manner can be corroborated and at times refined by the examination of the fossil forms present. The tracing and matching of the fossil content of separate rock outcrops (that is, the correlation process) eventually enabled investigators to integrate rock sequences in many areas of the world and construct a relative geologic time scale.
Scientific knowledge of the Earth’s geologic history has advanced significantly since the development of radiometric dating, a method of age determination based on the principle that radioactive atoms in geologic materials decay at constant, known rates to daughter atoms. Radiometric dating has provided not only a means of numerically quantifying geologic time but also a tool for determining the age of various rocks that predate the appearance of life-forms.
In other places there can be a finer balance. The origins of a piece of oral history are typically much more obscure than the historical context of written records or inscriptions. It can be extremely difficult to separate genuine traditions and stories that stretch back over many generations from more modern inventions or infiltrations. In Hawai’i, a very rich oral heritage existed until the early nineteenth century, of which only fragments now survive. Yet in assessing the significance of temple alignments in these islands, some of those surviving fragments may contain vital gems of information. They are of uncertain provenance, so must be used with extreme caution, but one would be unwise to simply ignore them and revert to statistics alone.
Where the only available evidence is archaeological, it is possible to use analogies from different cultures where other forms of evidence exist to suggest interpretations. Thus in the 1970s, the Scottish archaeologist Euan MacKie attempted to use the analogy of Maya society to argue (in support of theories, popular at the time, that many of the British megaliths were high-precision observatories) for the existence of highly skilled astronomer-priests in Neolithic Britain. However, this direct use of ethnographic or historical analogy is generally fraught with problems. Most archaeologists concluded, for a variety of reasons, that MacKie’s efforts were badly misguided. On the other hand, analogies can be very useful in challenging assumptions that might have been made too unquestioningly, and hence in suggesting new interpretative possibilities. It is generally assumed, for example, that any people who observed the changing rising and setting position of the sun on the horizon over the year must have understood that this regulated seasonal events. Yet while it is true that some of the Mursi, already mentioned, track the changing rising position of the sun on the horizon, the MURSI CALENDAR is based upon the moon. The sun is regarded as no more reliable a seasonal indicator than the behavior of various birds, animals, or plants. The Mursi example stops us leaping to conclusions about practices in the past by showing us that the range of possibilities is wider than we might have imagined.
In summary, where we have only archaeological evidence to go on, it may be possible to gain insights into prehistoric worldviews by recognizing symbolic associations in the material record. Analogy may be useful in the process of interpretation, but our conclusions will never be categorical. We can only ever have a certain degree of belief that a specific association had meaning to a particular group of people, although our belief may be strengthened or weakened by further evidence.
Where we have first-hand informants or can actually still witness long-standing cultural practices, we are in the strongest position to recognize aspects of other worldviews. Examples such as the modern Yucatec Maya village of Yalcobá in southern Mexico, where the structure of the cosmos is reflected in a whole variety of aspects of social behavior, show just how rich and complex these practices can be. Yet ethnographers can be misled by informants, especially if they ask the wrong questions—all too easy if they have very little initial understanding of the nature of the worldview they are studying. Added to this, sacred information is often withheld, or the anthropologist may not be at liberty to pass it on. There is also the additional danger that the ethnographer may succeed, unwittingly, in influencing the very worldview he or she is trying to investigate, so that a subsequent investigator is misled into thinking that certain modern knowledge was in fact indigenous. Finally, most of us are limited to approaching the cultural information indirectly, at best at second hand, which imposes a selectivity that is not of our choosing and a filter—that of the ethnographer’s interpretations— through which we are forced to view everything.
Historical accounts, whether by indigenous people themselves or by past ethnographers, are subject to all the problems just mentioned together with some additional ones. For one thing, an author who is no longer alive cannot be questioned, so there is no possibility of clarification or elaboration. For another, in interpreting a historical account it may be critical to appreciate the context in which it was produced.
Ancient written records directly relating to astronomy exist not only among the civilizations of the Middle and Far East. Perhaps the most extraordinary example produced in the American continent is the Maya DRESDEN CODEX, a pre-Columbian astronomical (or, more accurately, astrological) almanac. Both its complexity and level of detail are exceptional. In some cultures, other types of recording device encapsulated sacred information, including astronomical knowledge or calendrical data. One intriguing example is the QUIPU, bundles of knotted strings used in the Inca empire. A much more widespread practice, which did not produce any form of written record, was to embed sky knowledge and cosmological beliefs within myths that were transmitted from generation to generation orally. Storytelling may have been entertaining, but it could also have the deeper purpose of passing on wisdom. Creation myths often served to confirm a community’s rightful place in space and time, or to establish the genealogical credentials, and hence the social standing, of a king or leader. (Genealogies were not limited to human forbears. The KUMULIPO, a 2,000-line long Hawaiian creation chant composed in the eighteenth century, recounted in detail how chief Ka-‘I-i-mamao was related, ultimately, to everything in the world.) Some sacred stories were carefully learned and recounted, often in the context of formal ceremonies. Other tales might change in the telling, bringing many variations down to us but leaving intact the essential underlying substance and meaning.
The further we delve into the past, the more we find ourselves limited to the archaeological record—the material remains of past human activity. Silent alignments of stone temples and tombs, interplays of sunlight and shade that light up dark spaces only on rare occasions, symbols with unfathomable meanings but which resemble the sun or moon or familiar groups of stars—these form many of the most famous manifestations of ancient astronomy. But they also present the serious scholar with serious methodological problems. Every oriented structure must point towards some point on the horizon, and in all likelihood to one or more identifiable astronomical targets. Similarly, the majority of entrances and openings will let in a shaft of sunlight at some time of the year and day. The mere existence of (say) a solar alignment is no guarantee that this meant anything to the builders of a house, temple, or tomb. Since astronomical alignments can—and frequently will—occur completely by chance, we must do more than simply “butterfly collect” them if we are interested in what they actually meant to people in the past. There are two ways of proceeding: either to seek statistical confirmation— for example, by identifying a group of several monuments in which a certain type of astronomical alignment occurs repeatedly—or by finding corroborating archaeological evidence of different forms. An example of the former is the RECUMBENT STONE CIRCLES of northeast Scotland, which have a consistent orientation relating to the moon. Two different examples of the latter, also from Neolithic and Bronze Age Britain, are the THORNBOROUGH henges (large round embanked enclosures) in Yorkshire, England, and the cairns at Balnuaran of Clava in Inverness, Scotland.
In some cases, such as pre-Columbian Mesoamerica, we have both archaeological and other forms of evidence, including ethnohistory (accounts recorded during the early years of European contact), iconography, and written records. Integrating these diverse forms of evidence can be a considerable challenge. This problem is illustrated by the prolonged controversy that surrounded the putative Venus alignment at the so-called Governor’s Palace at the Maya city of Uxmal. Inscriptions on the building attest to a strong interest in the planet Venus, but the apparent orientation of the building toward an extreme rising point of the planet has generated much debate. In ancient Mesoamerica in general, the historical evidence relating to astronomy and calendrics is strong, and the archaeological evidence—for example in the form of alignments—tends to strengthen and corroborate this. If it were not for the accounts of the early Spanish chroniclers, the calendrical inscriptions, and the vital bark books (codices), we would simply have no idea of the sophistication and complexity of Mesoamerican astronomy.
Tuesday, December 21, 2010
The Nabataean kingdom was one of the wealthiest of the Client States which were a prominent feature on the Roman frontiers, especially in the east. Its capital at Petra is famous for its spectacular civic buildings and tombs. It was annexed by Trajan who created the new province of Arabia.
The Nabataeans were early nomadic Arabs who traveled across the deserts of Arabia for trade. Although not as well known as other ancient civilizations, the Nabataeans were trade savvy and developed ingenious hydraulic engineering systems, some remains of which can be seen in Petra today. These two elements combined enabled the Nabataeans to control important trade routes. They not only operated from Petra – the region that in the bible is called Edom – but also throughout Moab and other regions from southern Syria to the western Sinai. By the fourth century B.C. the Nabataeans controlled the spice and incense trade from Arabia to Mesopotamia.
Their efficient water storage techniques, which included hidden underground cisterns strategically located along their trade routes, allowed the Nabataeans to cross vast expanses of desert, brining frankincense and spices from Arabia and from the East to the Mediterranean. Thus Petra flourished in the first centuries B.C. and A.D., despite the extremely arid environment, by the engineering of a sophisticated hydrological system. The system brought water in channels and clay pipes from springs near Petra, notably from Ain Musa which is located in present-day Wadi Musa. The system also harvested the meager yearly rainfall and mitigated the effects of the rare downpours that would otherwise have produced destructive flash floods.
In continually seeking to improve their position in a trading network that included Greece, Persia, Rome, India, and Arabia and that stretched ultimately to China, the Nabataeans provided a conduit for goods and ideas among these groups. The architecture of Petra that survives today testifies to the exchange of cultural traits that occurred on a global scale even in ancient times. Tombs and buildings display Assyrian, Egyptian, Hellenistic, Babylonian, and Roman characteristics incorporated into a Nabataean style that, especially in its earlier expressions, owes much to the architectural tradition of the East.