Bands in Sandstone
1. Are joints or cracks visible within the granite?
2. Describe the bands. Are they random, repeating, concentric, jagged, uneven.....?
3. How wide are the bands at their widest point?
4. What color are the bands?
5. What pattern do these bands form? Square, circle, rectangle, triangle....?
6. Look very closely (and I mean closely) at the bands. What do you see in the middle of the bands? You might have to look at several bands to see the answer that I'm looking for.
The rounded erosional pattern of the granite bedrock outcrops is called spheroidal weathering, and is typical of granites around the world. The granite has been jointed or cracked in a rectilinear pattern and forms blocks. Water seeps into the rocks along the cracks and breaks down the minerals within the granite itself. The corners of these blocks are more susceptible to weathering and erosion as water attacks them from 3 sides at once. As the corners are eroded away, the remaining granite develops a characteristic rounded stacked boulder landscape like you see here.
At the coordinates you will see stains on the rounded granite rocks. These stains are called Liesegang bands (LEEZ-gahng) or Liesegang rings. They are patterns of iron-oxide, ranging from a reddish-brown to a yellowish brown in color. It is thought that these bands show where groundwater has oxidized the iron content of the biotite and hornblende minerals contained within the granite. The actual cause of which Liesegang rings form is not entirely understood and is still being researched at this time.
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Most of all……learn……and enjoy the view.
EarthCache approved by
Joe Baynes City of Prescott
Parks & Recreation Director