Sands-Arenology

Observations of Sand

Digital Microscopy - Upload photos

Create a subfolder for the location of your sand in the appropriate folder.  Upload four or more photos for each location, including a (1-3) 3 microscopic photos of the sand, (4) an aerial photo, and (5) a land-based scenic photo, and (6) a photo of the primary substrates from which the sand was formed. Label your folder and enclosed photos in a manner the following manner, substituting your specific location as appropriate.

Folder: Hana, Maui
  • Photo 1-3: Hana, Maui - sand
  • Photo 4: Hana, Maui - aerial
  • Photo 5: Hana, Maui - scene
  • Photo 6: Hana, Maui - substrates

Mapping

  • Plot all six photos data on MyMaps | (example: map 2015). 
  • Include paragraph of data from the survey.

Topics

  • Geology
    • tectonic processes
    • the rock cycle
    • weathering and erosion
    • stratigraphy
    • paleontology
    •  location of ancient seas & sea level changes.
    • water, wind and marine erosion
  • Chemistry 
    • Chemical profiles of minerals (mineralogy)
    • solubility and other reactions with the environment
    • chemical weathering 
  • Biology 
    • Some sand grains are actually marine life remains
    • Beaches can reveal the diversity, abundance and ecology of organisms that dwell in water.

Premises

  • Carbonate composition indicates biological origins of sand grains.
  • Degree of sand grain roundness indicates greater weathering, a function of age or distance traveled; composition influences the rate of weathering.
  • Sand grain size is positively related to energy of wateer movement, the larger the grains the stronger the wave movement needed to move them.

Inferences based upon analysis of Sand

Complete the following survey with regards to your sand sample.
  • Terrigenous Sands - Sands from the Land
    • Weathererd granite
      • contain clear quartz as well as dark and light minerals 
    • Weathered volcanics
      • often glassy and black
      • may include olive green or brick red
    • Silica based - shows no reaction to vinegar (5% acetic acid)
  • Biogenous Sands - Sands from the Sea
    • From skeletal fragments of marine plants and animals 
    • Waves carry pieces of coral, seashells, etc. and deposit on beach
    • Calcium carbonate (limestone), dissoplves in vinegar (5% acetic acid), producing small bubbles of carbon dioxide.

Appearance of Sand

  • Shape
    • Well-rounded
    • poorly rounded or angular
    • spherical
    • disk shaped
  • Angularity
    • very angualar
    • angular
    • sub-angular
    • sub-rounded
    • rlonded
    • well rounded

 


Grain Size

Sand is defined as: Small, loose grains of mineral, rock, or other naturally occurring material, with grain sizes between 1/16 mm and 2 mm.

Design and print your own mm graph paper.  Plot Measure the average size of the particles in your sample by placing grains on this paper. 

Determine the type of sand in your sample using a set of sieves. Arrange the sieves with the largest screen size (#5) on top, decreasing screen sizes in order below to the closed bottom container. Measure a sand sample by volume or weight. Place the sample into the top sieve, cover and shake the entire set with a back-and-forth motion. The particles should separate into their respective sizes.


Motion of environment

How swift was the water or wind movement in the sand you collected?  Where rivers flow or waves surge, sand moves.  The stronger the water movement, the larger the sand grains that are carried and/or kept in suspension.

  • Fast Current / Strong Waves - Where rivers run swiftly or waves are strong,
they can carry larger or heavier grains and build beaches of boulders or gravel. The finer materials keep on moving, you won’t find them here!
  • Slow Current / Weak Waves- Where rivers are slow or waves are weak,
they carry only small or light grains. As water movement weakens, even the smallest sands are dropped,contributing to deposits of fine sand.

Origin

Plutonic (Granite) - Granite rocks include of several different minerals, but quartz – made of silicon dioxide is the most durable to erosion. Quartz is often clear. Depending on the degree of weathering, granite sand may also include light-colored grains of the mineral feldspar or darker grains of hornblende, mica or magnetite. Where you find quartz sands, there must be some continental rocks somewhere.

Volcanic Origin – Sands of volcanic origin tend to be black, red, or green.

Meamorphic Origin – Sands that are of metamorphic origin often have garnet, a purple rock. If you have purple in your sample, it may indicate a history of metamorphosis.

Rock classification

Use the following keys to identify the samples provided.  Put your answer in this survey. 



 







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sand.pdf
(636k)
Norman Herr,
Mar 13, 2012, 10:21 PM
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