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Weathering

Weathering. Weathering. Weathering vs. Erosion Joints: Setting the Stage Physical (Mechanical) Weathering Chemical Weathering Products and Forms Made by Weathering Weathering Landscapes. 6. Weathering Landscapes.

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Weathering

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  1. Weathering

  2. Weathering • Weathering vs. Erosion • Joints: Setting the Stage • Physical (Mechanical) Weathering • Chemical Weathering • Products and Forms Made by Weathering • Weathering Landscapes

  3. 6. Weathering Landscapes • Consider a common rock – granitic rocks (granite, granodiorite, tonalite, diorite …) made up of interlocking minerals

  4. Decay of weak minerals (biotite, feldspar) separates grains and makes granite sand called - GRUS

  5. Grus producedmost rapidly where joints intersect

  6. Granular distintegration – seen on rock surfaces

  7. rounds edges of petroglyphs – blurring petroglyphs

  8. Crumbly distintegration – grains weathered to powder

  9. Grus erosion from joints creates rounded forms at Mt Rushmore

  10. Core stones made when corners of granite blocks weathered into grus

  11. Core stones in subsurface are “emerge” onto the surface as the grus washes away with rain and flowing water, because they are too big to be carried by water

  12. Grus washes away easily with rain, leaving piles of core stones - tors

  13. Tors (piled up core stones) very common in the Sonoran Desert

  14. Granite weathering took a long time in the subsurface (from groundwater) – spheroidal forms were then exposed by erosion of grus

  15. Erosion of weathered material by flaking (fingernail thick)

  16. Erosion of weathered material byScaling – thicker

  17. Rock Art Panels Host Dozens of Weathering Forms • How many can you identify?

  18. Rock Art Panels Host Dozens of Weathering Forms • How many can you identify?

  19. Encourage Site Stewardship to Protect Priceless Cultural Heritage

  20. Imagery seen in this presentation is courtesy of ASU faculty, Paradise Valley and Mesa CC faculty, students and colleagues in other academic units, individual illustrations in scholarly journals such as Science and Nature, scholarly societies such as the Association of American Geographers, city, state governments, other countries government websites and U.S. government agencies such as NASA, USGS, NRCS, Library of Congress, U.S. Fish and Wildlife Service USAID and NOAA.

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