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Rock Art Stability Index (R.A.S.I)

Rock Art Stability Index (R.A.S.I). An introduction to the weathering And erosion of rocks and rock art. First, Let’s Define Rock Art…. There are several types: Pictographs Petroglyphs Geoglyphs Intaglios. Pictographs. Images Painted on to the Surface of a Rock. Petroglyphs.

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Rock Art Stability Index (R.A.S.I)

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  1. Rock Art Stability Index (R.A.S.I) An introduction to the weathering And erosion of rocks and rock art

  2. First, Let’s Define Rock Art… • There are several types: • Pictographs • Petroglyphs • Geoglyphs • Intaglios

  3. Pictographs • Images Painted on to the Surface of a Rock

  4. Petroglyphs • Images carved or etched into rocks • This image is from the Petrified Forest National Park, in AZ

  5. Geoglyphs • Also called Rock alignments • These are rocks placed on the ground to form a pattern or image Image: www.chile.ca

  6. Intaglio • Dirt, rock, or material removed in order to form an image Image: Bureau of Land Management

  7. So, What is R.A.S.I&Why Should I Care? • R.A.S.I. Stands for: • Rock Art Stability Index • This helps us tell how much danger the rock art is in of being lost…

  8. Why Should I care? • Rock Art is a form of a Cultural Resource. • It tells us about : • Native American People and Cultures • People who have come and gone in the past • It gives us an archaeological record

  9. How Old IS it? • Age of the rock art varies from 100 years or less to several thousand years old. • The older rock art was carved before the invention of modern tools • Rocks were used as tools, and images were pecked into the rock by hand.

  10. Why is it in Danger? • Rock Art is a precious, natural resource that is not renewable – • Erosion • Weathering • Vandalism • Theft Once it’s Gone…

  11. It’s Gone Forever… UNLESS…

  12. We Can Preserve it in Some Way • This is where RASI comes in… • We take photos… • We analyze the danger the rock art is in of being lost • We report it to the National Park Service

  13. Then What? • The information we collect is put into a Database… • Then, The National Park Decides • How to go about Preserving The Rock Art

  14. Why Am I Learning This? • Research Shows… • Students learn better when they apply something they learn • This gives a hands on learning opportunity • It’s More Fun This Way

  15. You will be looking at the panel in a few ways.. Don’t panic, these will be explained as you go along… • The geological setting • Which is the area surrounding the panel • Then general weakness of the panel itself • Large erosion events • These are major events about to happen • Small erosion events on the panel – this is where you get up close to the panel and look for smaller types of weathering • Rock Coatings actually on the panel • Vandalism and other issues

  16. Fissures – Cracks in the Rock • Dependent on stone lithification • Goes along with the bedding plane • Independent of Stone lithification: • Goes against the bedding plane of the rock • More Examples:

  17. Changes in Textural Anomalies • The texture of the rock has banding, spots, or concretions

  18. Rock Weakness –Moh’s Hardness scale

  19. Weaknesses of the Rock Art Panel – this is looking at the entire panel • Fissuresol • dust that gets into the cracks of rocks and weakens it from expansion and contraction during temperature changes • It leaves a ‘scar’ when the rock breaks off • The orange and black is the dust coating left from the break

  20. Roots • Look at the panel, and see if there are roots growing in the panel • The second part asks if there are plants on or near the panel

  21. Scaling & Flaking • Scaling • pieces coming off that are a few cm thick – like the width of a hand • Flaking • smaller sizes pieces flaking off – about the thickness of a corn flake or smaller

  22. Splintering • Fissures follow stone structure – • Many in layers • Looks like a book that has gotten wet

  23. Undercutting • This is where a large portion of the rock or soil is missing beneath the panel – Usually caused by water flow

  24. Weathering Rind Development • Weathering Rind – • Looks kind of like an orange peel type texture • Bumpy, uneven texture • Included a picture without weathering rind to demonstrate the difference.

  25. Evidence of Large ErosionEvents on and Below The Panel • Now you are going to look around the panel • Identify Larger Erosion Events • These are things you can see from a short distance

  26. Anthropogenic Activities(Anthro – Human) • This refers to any current activities by people • Near a hiking trail? • Trash around? • Vandalism? • Judge this by how much of these and similar activities are happening around the site

  27. Smaller Events On the Panel • This is where you get up close and personal to your panel • These are events on a smaller scale • Sometimes your really need to look up close to be able to see these

  28. Abrasion • From Sediment Transport by Water • Water flow carries dirt, sand, and debris, • This causes rocks to wear down • If there is rock art on a rock that is in the path of water, it will slowly disappear

  29. AnthropogenicCutting • Includes • Carving • Chiseling • Bullet impact • Other impact • Does NOT include: • The Rock Art itself • Note about classification: • If it’s 50 years old or older: Artifact • If it’s 100 years old or older: Archaeological

  30. Aviolization • Pitted or Honeycombed appearance • Usually in ‘clusters’ not just one pit/hole • Tends to continue to expand and merge together

  31. Crumbly Disintigration • This is where parts of the rock are crumbling off • Texture of Feta Cheese • Can look ‘Powdery’

  32. Flaking • Single or Multiple • Millimeter-scale • Harder to see • Get up close for this

  33. Flaking of the Weathering Rind • Even Smaller Than Flaking • Small flakes in the Weathering Rind • We Saw the Formation of Weathering Rind in a Previous Slide

  34. Granular disintegration • Similar to Crumbly Disintegration • Smaller, sand size debris left over • Most frequently sandstone and granitic

  35. Lithobiont pitting • Lithobionts are a Fungus that Grows on the Rock and Eats it • Leaves a Pitted Appearance in the Surface of the Rock • Can Look Similar to Aveolization

  36. Lithobiont release • when the "dam" of weathered rind decayed rock erodes • Leaves a visible scar in the rock • Happens when the lithobionts die

  37. Loss parallel to stone structure • bedding or foliations • Rock Cracks and Separates

  38. Rock coating detachment • Usually incomplete • Includes paint material in pictographs • Coating on rock starts to detach

  39. Rounding of petroglyph edges (or blurring of pictograph images) • Take the assumption that they were crisp and sharp when created • Can be blurred a little or almost un-discernible

  40. Rounding of petroglyph edges (or blurring of pictograph images) • Take the assumption that they were crisp and sharp when created • Can be blurred a little or almost un-discernible

  41. Textural Anomaly Features Erode Differentially • Clay lenses • Cementation • Differences • Nodules

  42. Rock coating present • Rock coatings vary • Most rock will have some coating • Rock coatings help protect the rock • This is a negative number on your assessment sheet

  43. Case Hardening • Similar to Rock Coatings • But becomes thicker • If you knock on it, it will sound hollow • Although it protects the rock, when it detaches, there is loss

  44. Now, Go RASI! Step 1 • Log Into Course Assign • Answer Questions • Submit your Lab

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