arch. lecture 1 Flashcards

Question

Indirect Dating

Answer 1

analysis of materials associated with a given object. depends on context.

Answer 2

* earlier or later than something else. * ordering things in a sequence. * not as precise.

Answer 3

dated to a specific year either Before Present or according to a calendrical system.

Answer 4

* based on the sequential laying down of strata * 17th century - Law of Superposition: "where one layer overlies another, the lower layer was deposited first" * strata are created both by humans and natural processes * Potential Problem: Disturbance: * e.g. garbage pits * burrowing animals (rodents, dogs) * floods washing layers away, redeposition

Answer 5

* typological sequences, meaning artifacts change over time * Technology and fashions change (eg. cars, clothes, music, etc.) * some artifacts change more quickly and regularly than others * eg. pottery; arrowhead types * Stylistic Seriation * most often pottery - types or styles * presence / absence

Answer 6

* more precise means of determining an ordered sequence * based on the fact that any artifact type will be initially rare, then well-accepted, and then die out as it is replaced. * measuring changes in the proportional abundance (frequency) of artifacts * limitations: the artifact types must occur over a large region, and must occur in significant frequencies

Answer 7

* Horizontal stratigraphy * in some areas, occupation moved horizontally in a predictable way. * e.g. series of beach ridges are formed as a waterbody recedes * e.g. Cape Krusenstern, Alaska * Limitations: * Beach ridges must be formed in a regular fashion * Activity must be confined to waterfront beach ridge

Answer 8

* e.g. dates on grave stones, monuments, written documents calendars * Greeks - from date of first Olympics - 776 BCE * Muhammad's departure from Mecca = 622 CE * Egypt, China in terms of successive dynasties * Limitations: * must be long, with no gaps * e.g. dynasties need to list all kings * must be linked to a known date, or else it is relative

Answer 9

* Obsidian = volcanic glass - common stone tool material * When fractured - edge begins to absorb water (= “hydration”) * hydration penetrates into the stone at a known rate – can be measured ## Footnote Limitations: * regionally specific - depends on temperature, moisture, etc. * each obsidian source is different

Answer 10

* temperate areas - trees dormant during winter - well-defined growth rings which vary by year in regular patterns * Today - many sequences - oak trees from southern Germany – 11,000 years * Sophisticated uses, e.g. sequences of construction and occupation of complex sites ## Footnote Limitations: * requires preservation * reuse of old wood, e.g. as beams (date is of cutting, not use) * need a regional chronology - complex and time-consuming * useful only outside of tropics

Answer 11

* Looks at large-scale reversals of Earth’s north – south polarity. * used only occasionally, to confirm other dating methods

Answer 12

* Willard Libby 1949 * a radiometric dating method, based on radioactive decay of isotopes * (isotopes = different forms of an element with different “atomic weights”, ie., different numbers of protons and neutrons in the nucleus) * some isotopes are stable, others are unstable – unstable isotopes gradually decay, changing into stable elements * can be used to date objects, if you know: * original amount of isotope * amount remaining at present * rate of radioactive decay * rate of decay is measured by a half-life = the time it takes for half of the isotope to decay ## Footnote * Most common form of carbon = Carbon 12 (stable) * Cosmic radiation - produces unstable Carbon 14 * plants absorb C14 in carbon dioxide during photosynthesis; eaten by herbivores, eaten by carnivores * continually replaced during life; until death * After death, since C14 is unstable, it decays gradually * half-life = 5730 years * as C14 decays (converting to N14), it releases radioactive beta particles * Geiger counter used to measure beta emissions * allows estimate of amount of C14 left in sample – this amount indicates the age of the sample

Answer 13

* conventional dating - measure beta emissions - requires about 5 gm pure carbon = 10 gm charcoal, 200 gm bone. * AMS - measures the amount of C14 directly - requires only tiny samples: * artifacts themselves can be dated * small or valuable objects can be dated * if organics are rare, single seeds, twigs, etc. can be dated

Answer 14

* contamination before sampling: carbon in groundwater, modern plant roots, etc. * contamination during sampling: cardboard labels, glue, mould, etc. * sample is older than context (e.g., old wood used to build house) * some materials contain ancient carbon (eg. sea mammal bone) * maximum date about 50,000 years

Answer 15

* another form of radiometric dating * used to date volcanic rock, not artifacts or other human products * minimum age 5,000 years, no maximum age (half life 1,330,000,000 years) * useful in regions with lots of volcanism - when rock is heated, drives out all Argon, and then potassium decays to argon over time at known rate.

Answer 16

* with all dating methods, demonstration of association is key. * generally, try to use at least two methods to confirm date. * e.g. stratigraphy + C14. * every dating method has its problems and limitations.

Answer 17

* the archaeological record is the sum of all physical evidence about the past that survives to the present, i.e. objects plus their context. * but not all behaviour will leave material traces. * because of intervening cultural and natural processes, the archaeological record is not usually a direct reflection of past behaviour. * archaeologists must avoid the "Pompeii Premise".

arch. lecture 1 Flashcards

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