Archaeological Dating, Survey and Excavation

Types of Dating Methods

TYPOLOGY AND CROSS-DATING

HISTORICAL DATING

DENDROCHRONOLOGY

SCIENTIFIC DATING TECHNIQUESABSOLUTE TECHNIQUES DERIVATIVE TECHNIQUES

Typology and Cross-DatingTypology is not, strictly speaking, a dating method, but a means of placing artefacts into some kind of order. Typology seeks to identify and analyse changes that will allow artefacts to be placed into sequences.These techniques place assemblages of artefacts into relative order. Petrie used sequence dating to work back from the earliest historical phases of Egypt into pre-dynastic Neolithic times, using groups of contemporary artefacts deposited together at a single time in graves. Seriation (Cross-dating) was developed in the USA to place in order finds from strata or other kinds of assemblages such as potsherds collected from the surface of sites.

Historical DatingPrehistorians sometimes overestimate the accuracy and detail of frameworks based on historical evidence; in practice, early written sources may provide little more information than a scatter of radiocarbon dates. The extent of documentation varied considerably in 'historical' cultures and the information that survives is determined by a variety of factors. E.G. If a context containing burnt debris and broken artefacts is excavated on a site from a historical period, it is tempting to search the local historical framework for references to warfare or a disaster in the region, and to date the excavated context accordingly.

Dendrochronology(dendron = tree, chronos = time, logos = word = the science of): The science that uses tree rings dated to their exact year of formation to analyze temporal and spatial patterns of processes in the physical and cultural sciences. Dendroarchaeology-The science that uses tree rings to date when timber was felled, transported, processed, or used for construction or wooden artifacts. Example: dating the tree rings of a beam from a ruin in the American Southwest to determine when it was built.

© 2002 by Henri D. Grissino-Mayer.

Dendrochronology and Cross-Dating

© 2002 by Henri D. Grissino-Mayer.

Absolute Techniques

Radiocarbon dating Potassium-argon (40K/40Ar) and argon-argon dating (40Ar/39Ar) Uranium series dating-decay of uranium to helium/lead.Fission-track dating-microscopic tracks in glassy material.Luminescence dating-heating of crystalline material.Electron spin resonance (ESR)-electrons subjected to radiation then resonate.

Radiocarbon datingCarbon 14- one peaceful by-product of accelerated wartime research into atomic physics and radioactivity in the 1940s. The rate of decay of 14C, which has a half-life of 5730 (±40) years, is long enough to allow samples of carbon as old as 70,000 years. AMS- Accelerator Mass Spectrometry

Potassium-argon (40K/40Ar) and argon-argon dating (40Ar/39Ar)

Ideal for dating early hominid fossils in East Africa. They occur in an area that was volcanically active when the fossils were deposited between one and five million years ago.

DERIVATIVE TECHNIQUES Protein and amino acid diagenesis dating

Bones, teeth and shells contain proteins that break down after death, and the most commonly investigated products of decomposition are amino acids. Amino acid racemization dating (AAR) measures changes between these amino acids' L- and D-forms; their ratio is an indication of age.

Obsidian hydration dating Obsidian was a popular alternative to flint for making flaked tools in many parts of the world. As soon as a fresh surface of obsidian is exposed, during the process of making it into a tool, a microscopically thin hydration rim begins to form as a result of the absorption of water.

Archaeomagnetic dating The position of magnetic North wanders around the North Pole, and even reverses completely to the South Pole for extended periods on a geological time-scale. From any reference point its position is measurable in terms of two components: movement up or down (inclination or 'dip') and from side to side (declination).

Survey and ExcavationResearch Design

Finding Archaeological Sites

Excavation

Types of Sites

Research DesignDesign and Formulation

Background ResearchResearch design

ImplementationFundingResearch team membersPermission

Data AcquisitionField ResearchConservationInitial Artifact processing

Processing and Analysis

Lab analysis

Curation

Interpretation

Final Report

Finding Sites Accidentally

Iceman-1991Lascaux

Archaeological Surveysurface surveysubsurface excavation

stp auger bank cuts

Remote SensingGround penetrating radarmagnetic resistivity

Aerial Photography

mounds

crop marks

 Satellite Imagery

 Geographic Information Systems (GIS)

Iceman-1991 Austrian/Italian Alps

Ground Penetrating Radar

Magnetic Resistivity

Aerial Photography

Samarra' is a town on the east bank of the middle Tigris in Iraq, 125 km north of Baghdad, Between A.D. 836 and 892 it was the capital of the Abbasid Caliphs. Samarra’ expanded to an occupied area of 57 km², one of the largest cities of ancient times.

Vertical ExcavationDigging limited areas for info on stratigraphy and dating“Test Trenching”

Area ExcavationHorizontal excavation“Block Areas”

Underwater

ToolsBackhoes, Bulldozers

Picks, shovels, trowels

Dental picks, brushes

Recording

Stratigraphy

 

Excavation

Vertical Excavation

Area Excavation

Underwater Archaeology

Types of Sites

Habitation SitesOpen campsites

Villages

Caves & Rockshelters

EarthworksMounds

Forts

Shell Middens

 Ceremonial Sites

Architectural Sites

Burials and Cemetaries

Historic Sites