Where is Puddingstone found?
Conglomerate (Jasper/Chert and Quartzite clasts in a fine-grained matrix)
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Open the appPuddingstone 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 Puddingstone
Michigan, USA (Drummond Island, Northern Lower Peninsula)
Famous for the 'Michigan Puddingstone' (Ozark Puddingstone), characterized by white quartzite clasts in a reddish-brown jasper matrix, or vice-versa. Found in glacial till and outwash deposits, originating from the Precambrian Lorrain Formation in Ontario, Canada.
Hertfordshire, England
The 'Hertfordshire Puddingstone' is a well-known variety, consisting of rounded flint and chert pebbles cemented by a siliceous matrix. It is found in the Paleocene Reading Formation.
Ontario, Canada (Lorrain Formation)
The source of many glacial erratics found in Michigan, this Precambrian formation contains extensive deposits of quartzite and jasper conglomerate.
Various locations globally
Puddingstone-like conglomerates can be found in numerous sedimentary basins worldwide where conditions for their formation existed, often associated with ancient river systems or glacial activity.
Collecting tips
- Look in Glacial Deposits. Many prominent puddingstone occurrences, especially in North America, are found as glacial erratics in till and outwash plains, transported far from their source.
- Examine Riverbeds and Alluvial Fans. These high-energy environments are prime locations for the deposition of rounded clasts that can eventually form conglomerates.
- Check Outcrops of Sedimentary Formations. Geological maps can help identify specific sedimentary formations known to contain conglomerate layers.
- Look for Contrasting Colors and Rounded Shapes. The key visual identifier is the distinct contrast between the rounded clasts and the surrounding matrix.
Quick Check
- Color:
- Variable, often with contrasting colors between clasts and matrix (e.g., white clasts in red matrix, or vice-versa).
- Luster:
- Dull to vitreous.
- Streak:
- Not applicable for a rock; individual mineral components would have their own streak (e.g., quartz/chert: white).
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