ANT 2100 Exam 2 Guide Chapters 5 8 Chapter 5 Geoarchaeology 1 Applies concepts ad methods of geosciences to archaeological research a Objectives techniques i Place sites and artifacts in a context through the application of stratigraphic principles and dating ii Understand the natural processes of site formation modification and destruction 2 Flat area don t show erosion like sloped Plowing has an impact a b wind erosion where vegetation is sparse causes deflation 3 The law of superposition a b a in pile of sedimentary rocks undisturbed by folding or overturning the strata on the bottom were deposited first the layer above next and so on principle seems simple but wasn t formulated until 17th century by Nicolaus Steno 4 Footprints at Laetoli It was believed that bipedalism was response to tool use i Mary Leakey used knowledge of region to hypothesis that the footprints at Laetoli were 1 000 000 older then the oldest known tool use b Leakey worked with geologists Robert Drake and Garness Curtis to date the footprints i Used potassium argon dating processes ii Prints dated between 3 49 and 3 56 million years old iii Proved humans bipedal prior to tool use 5 6 Depth is not necessarily guarantee of great antiquity Stratigraphic profile a Laetoli i Deposition erosion ongoing Is a dynamic process with great variability across time and space 1 2 Multiple dates if possible so as to cross date the material b Mazamas ash fall 6845 years ago 7 Geo probes used to get a soil sample from depths without a large excavation i Formed crater lake can be seen over great distance a Geoprobe is a soil sample sealed in plastic tube that allows for sample of soil types layers and strata information and analysis 8 9 Color composition Reading Gatecliff s Dirt a Waves or straight physical features for field observation of soil and strata information a b c Gatecliff shelter has 40 stratigraphic profile covering more than 7000 yrs Sediments resulted from natural process and human behavior Physical stratigraphy is placed in a table until it sterile soil reached 10 Deposits a b c 11 Context a Alluvian water carried deposits Colluvial gravity carried deposits either by falling or slides Eolian wind carried sediments Systemic context is a living behavioral system where artifacts are part of the ongoing system of manufacture use re use and discard b Once artifacts enter the ground become part of the archaeological record and context 12 Formation processes in system context a Four key processes in the systemic context that influence site creation i Cultural deposition ii Reclamation iii Disturbance iv Reuse 13 Cultural deposition a Dominant factor in forming the archaeological record i Discard 1 2 Wears out Everything eventually breaks ii Loss 1 2 iii Caching 1 iv Ritual Lose arrow that misses target Falls during travel Some items intentionally left behind 14 Reclamation processes 1 Grave goods a Human behaviors that result in artifacts moving from the archaeological context Scavenging beams from an abandoned structure for use in a new one i 15 Cultural disturbance processes a Human behavior that modify the artifacts in archaeological context i Dam building farming and construction of houses pits hearths 16 Reuse processes i Recycling a Object moves through a series of behavioral settings before it enter archaeological context 1 2 Potshards are ground up and used as temper in manufacture of other vessels Broken projectile points re chipped into dills 17 Formation processes in archaeological context a Objects have host of natural processes that effect the objects b c Processes determine whether organic material preserved and where it s found Called taphonomy 18 Natural formation processes i Process in which trees and plants affect the distribution of artifacts a b Floralturbation Faunaalterbation c Cryoturbation i Process in which animals from large game to earthworm affect the distribution of material 1 Krotovina a Animal burrows move left right up down i Process in which freeze thaw activity of soil pushes larger artifacts to the surface 1 Frost heaving 19 Natural formation processes a Argilliturbation i Process in which wet dry cycles in clay rich soils push artifacts upward as sediment swells with rainy season and down with the dry season 1 Growing rocks b Graviturbation i Process in which artifacts move downslope through gravity 20 Artifacts become oriented to the direction of river flow 21 Every environment presents different taphonomic issues and environment conditions Chapter 6 Chronology building how to get a date 1 Absolute dating 2 Relative dating Chronometric a b Dating provides estimate of age in years based on radioactive decay a Whether an object is older or younger than other objects or strata b Keys to relative dating i ii The law of superposition The index fossil concept 3 Stratigraphy and superposition a b Geology basically Law of superposition i Charles Lyell and Steno proposed ii Higher the strata are younger than the lower strata as long as undisturbed 4 Index fossil concept The idea that strata containing similar fossil assemblages are of similar age a b Mega fauna beer bottle with date fluted point c Fossils of certain extinct creatures found only in certain strata 5 6 7 8 Biostratigraphy Shore line dates Varve dating Biostratigraphy a a a Uses evolutionary changes in well known species for dating a Uses ancient shore lines for dating reference i Cape krusentern gulf coast of Florida cape Canaveral ii Can be used in deserts as well Annular fluctuation in sediment composition in cold lake bottoms Dating based on evolutionary changes within evolving living lineage i Paleontology zooarchaeology ii Megafuana in north America 10 000 yrs BP iii GBY site 780 000 9 Large scale catastrophes can provide a date estimates as well a Mt Mazama Ash i ii Eruption that affected miles Formed Crater Lake 10 Serration Relative dating method a b Orders artifacts with idea one cultural style slowly replaces another Illumination in Pa grave markers ceramics biface tools i 11 Temporal types Similar to index fossils a b Materials that can be associated with specific periods of time c Does not work artifacts that show little change over time 12 Tree ring dating a Charcoal or with at least 20 rings Regional sequences must be present 13 Cross dating b a b c Common indicators Compare similar items Dendrochronology i Most accurate ii One tree ring a year iii Rings vary in width iv v Must be a sensitive species Sequence