Why a new weathering index for rock art?

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Why a new weathering index for rock art?

• Ron Dorn
• Arizona State University

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Many Different Strategies exist to Document and
Diagnose Stone Decay
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Positive most detailed clearest subdivision of
weathering forms
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AndCoolColorCodes
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Not Appropriate for the Rock Art Problem

• Fitzners strategy way too expensive
  destructive
• Building strategies fit for fresh rock
• Engineering strategies require too much sampling
  expensive
• Others too focused on a specific issue (e.g.
  temperature, chemical weathering)

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Rest of Talk Movie PreviewJump ahead and show
you results so you can judge intuitively if our
strategy works
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Scale and Consistency
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Excellent Condition Why?

• Largest issues are plant growth near panel, some
  scaling of the rock, and detachment of the rock
  varnish
• Step 6 (Vandalism) is of minor concern because
  site is Deer Valley Rock Art Centers

• Basalt talus tends to display very little
  evidence of weathering and erosion

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Good Condition Why?

• Largest issues are plant growth near panel, some
  scaling of the rock, and detachment of the rock
  varnish
• Step 6 (Vandalism) is of minor concern because
  site is on private land with a site steward

• Silicified dolomite bedrock has few weaknesses
  for weatherings

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Problems Why?

• Despite strong granite rock, abundant fissures
  (joints)

• Largest issues are granular distintegration,
  fissuresol wedging, undercutting, and lichens
• Step 6 (Vandalism) is a substantial concern
  because site is in a metropolitan area and is
  receives heavy visitation

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30 (raw score) 20 50

• Stage 6
• could add
• 20 points
• to reflect
• vandalism
• concern

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Problems Why?

• Largest issues are weakness of the sandstone,
  development and then flaking of the weathering
  rind, and splintering along bedding planes

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Problems Score 33
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Why problems with this panel?

• Large issues are scaling, undercutting
• Site manager might put this site in great
  danger because of visitor use abrade panels

• Also flaking, granular disintegration, salt
  efflorescence, detachment of the pictograph paint

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Great Dangers Biggest Issues

• Salt Efflorescence

• Fluvial Abrasion

• Flaking of Weak Sandstone

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Severe Dangers A host of issues

• Lots of fissures, weak rock, wedging by
  fissuresols, plant growth, scaling, splintering,
  undercutting, development and erosion of
  weathering rinds, crumbling of rock under
  lichens, granular disintegration, flaking,
  detachment of rock coatings, scaling, chalking,
  graffiti, and salt efflorescence

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Display Options
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Why a new weathering index for rock art? Because
its time weathering nerds stepped up to the plate
and helped with a global crisis