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

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