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Archaeological Dating, Survey and Excavation

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Presentation on theme: "Archaeological Dating, Survey and Excavation"— Presentation transcript:

1 Archaeological Dating, Survey and Excavation

2 Types of Dating Methods

3 Typology and Cross-Dating
Typology 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.

4 Historical Dating Prehistorians 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.

5 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.

6 Dendrochronology and Cross-Dating
© 2002 by Henri D. Grissino-Mayer.

7 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.

8 Radiocarbon dating Carbon 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

9 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.

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).

11 Survey and Excavation Research Design Finding Archaeological Sites
Types of Sites

12 Research Design Design and Formulation Implementation Data Acquisition
Background Research Research design Implementation Funding Research team members Permission Data Acquisition Field Research Conservation Initial Artifact processing Processing and Analysis Lab analysis Curation Interpretation Final Report

13 Finding Sites Accidentally Archaeological Survey Remote Sensing
Iceman-1991 Lascaux Archaeological Survey surface survey subsurface excavation stp auger bank cuts Remote Sensing Ground penetrating radar magnetic resistivity Aerial Photography mounds crop marks  Satellite Imagery  Geographic Information Systems (GIS)

14 Iceman-1991 Austrian/Italian Alps

15 Ground Penetrating Radar

16 Magnetic Resistivity

17 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.

18 Excavation Vertical Excavation Area Excavation Underwater Tools
Digging limited areas for info on stratigraphy and dating “Test Trenching” Area Excavation Horizontal excavation “Block Areas” Underwater Tools Backhoes, Bulldozers Picks, shovels, trowels Dental picks, brushes Recording Stratigraphy

19 Vertical Excavation

20 Area Excavation

21 Underwater Archaeology

22 Types of Sites Habitation Sites Caves & Rockshelters Earthworks
Open campsites Villages Caves & Rockshelters Earthworks Mounds Forts Shell Middens  Ceremonial Sites Architectural Sites Burials and Cemetaries Historic Sites

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