Stratigraphy is like reading a history book written in layers of dirt. By studying these layers, archaeologists can piece together the story of a site, from oldest events at the bottom to newest at the top.
Understanding stratigraphy helps us uncover how people lived and how their cultures changed over time. It's like peeling back layers of an onion, revealing the past one layer at a time.
Principles of Stratigraphy
Concept of stratigraphy
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Top images from around the web for Concept of stratigraphy
Relative Ages of Rocks | Earth Science View original
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Overview of Relative Age and Orientation of Geologic Layers – Laboratory Manual for Earth Science View original
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The Geologic Time Scale – Physical Geology Laboratory View original
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Relative Ages of Rocks | Earth Science View original
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Overview of Relative Age and Orientation of Geologic Layers – Laboratory Manual for Earth Science View original
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Study of layered materials (strata) and their
Layers deposited over time, with oldest at bottom and youngest at top (sedimentary rocks, archaeological sites)
Crucial in archaeology for establishing relative chronology, interpreting sequence of events, and providing context for artifacts within layers
Helps understand cultural changes and human activities over time (transition from hunter-gatherer to agricultural societies)
Law of superposition
In a sequence of undisturbed layers, oldest layer is at bottom, and each successive layer is younger than one below it
Applies to sedimentary rocks and archaeological sites
Allows archaeologists to establish relative dates for artifacts and
Artifact found in lower layer is older than one found in upper layer (pottery shards, stone tools)
Helps determine order in which events occurred at a site and provides framework for understanding cultural changes over time
Transition from one cultural period to another (Paleolithic to Neolithic)
Principles of stratigraphic relationships
: layers deposited in nearly horizontal position
Deviations from horizontal indicate later disturbances or deformation (folding, faulting)
: layers extend laterally until they thin out or reach edge of depositional basin
Layers can be correlated across a site or region (ash layer from volcanic eruption)
: feature that cuts across another is younger than feature it cuts
Establishes relative chronology between features (walls, pits, intrusions)
Example: a pit dug through an existing wall is younger than the wall
Types of stratigraphic units
Layers (strata): distinct, relatively uniform units of sediment or soil deposited horizontally
Represent a specific period or event in site's formation (flood deposit, occupation layer)
: small, lens-shaped deposits within a layer
Often represent localized activities or short-term events (hearth, trash pit)
Features: non-portable elements of an archaeological site
Can be constructed (walls, buildings), excavated (pits, ditches), or naturally formed (post holes, tree roots)
Provide information about site structure and human activities (storage pits, burial sites)
Interpreting Stratigraphic Sequences
Using stratigraphic sequences to reconstruct past events and environments
Stratigraphic sequences provide a timeline of events at an archaeological site
Oldest events at bottom, most recent at top
Layers represent different periods of occupation, abandonment, or destruction
Archaeologists use stratigraphic sequences to:
Infer changes in human activities over time (shift from hunting to farming)
Reconstruct past environments and landscapes (climate change, deforestation)
Identify periods of occupation, abandonment, or destruction (natural disasters, wars)
Stratigraphic sequences can be correlated with other sites in the region
Establishes a broader chronology and understanding of cultural interactions (trade routes, migration patterns)
Example: a distinctive pottery style found in multiple sites can indicate cultural exchange or shared traditions