Where is River Rock found?
Sedimentary clast, likely Quartzite or Chert
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Open the appRiver Rock occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find River Rock
Riverbeds and Banks
Ubiquitous in active and ancient river channels, floodplains, and terraces worldwide.
Alluvial Fans
Deposits at the base of mountains where streams emerge from confined valleys onto flatter plains.
Glacial Outwash Plains
Areas where meltwater streams from glaciers have deposited sorted and rounded sediments.
Collecting tips
- Look for Water-Worn Shapes. The most distinctive feature is the rounded, smooth shape, indicative of transport and abrasion by water.
- Examine Local Geology. The composition of river rocks will reflect the bedrock geology of the upstream drainage basin. Knowing the local geology can help predict the types of rocks you might find.
- Check for Hardness. Many river rocks are composed of hard, resistant materials like quartz, which will scratch glass (Mohs hardness 7).
Quick Check
- Color:
- Variable (white, gray, black, brown, red, green)
- Luster:
- Dull to vitreous
- Streak:
- White (for quartz-rich clasts); variable for others, often not diagnostic for the clast as a whole.
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