Where is Graptolitic Shale found?
Shale (sedimentary rock) with Graptolithina (fossil)
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Open the appGraptolitic Shale 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 Graptolitic Shale
United Kingdom
Classic localities in Wales (e.g., Builth Wells, Aberystwyth) and the Lake District (e.g., Skiddaw Group) are renowned for their abundant and well-preserved Ordovician and Silurian graptolites.
Scandinavia (Sweden, Norway)
Significant graptolitic shale sequences, particularly in Sweden (e.g., Scania) and Norway, providing key biostratigraphic markers for the Ordovician and Silurian.
North America (USA, Canada)
Found in various regions, including the Appalachian Basin (e.g., New York, Pennsylvania, Quebec), Oklahoma, and Nevada, within Ordovician and Silurian marine successions.
Australia
Southeastern Australia (e.g., Victoria, New South Wales) has extensive graptolitic shale deposits, particularly from the Ordovician and Silurian periods, crucial for regional biostratigraphy.
China
Numerous localities, especially in South China, yield exceptionally well-preserved graptolites from the Cambrian to Silurian, contributing significantly to global graptolite research.
Collecting tips
- Look for Outcrops. Search for exposures of Ordovician and Silurian marine sedimentary rocks, particularly in road cuts, stream beds, quarries, and coastal cliffs. Graptolitic shales are often interbedded with other fine-grained sediments.
- Examine Bedding Planes. Graptolites are typically preserved as flattened impressions on the bedding planes of the shale. Carefully split thin layers of shale to reveal the fossils. A geological hammer and chisel are useful tools.
- Identify Dark, Carbonaceous Films. Look for dark, often shiny, dendritic, or saw-blade-like patterns against the lighter background of the shale. These are the carbonized remains of the graptolite colonies.
- Consult Geological Maps and Guides. Utilize local geological maps and field guides to pinpoint known graptolite localities. These resources often provide detailed information on specific formations and fossil horizons.
- Safety Precautions. When collecting, always wear appropriate safety gear, including eye protection and gloves. Be aware of unstable slopes and falling rock. Obtain permission before collecting on private land or in protected areas.
Quick Check
- Color:
- Dark gray to black with black fossils
- Luster:
- Dull to earthy (rock), slightly metallic/carbonaceous (fossils)
- Streak:
- Gray to black
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