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Photos: own photos
Ammonites are no longer living creatures, but their fossils are formed through a complex process called fossilisation. 🐚 This process begins after an ammonite dies.
The steps of fossilisation
Death and sedimentation: When an ammonite dies, its shell sinks to the sea floor. There, the soft body is decomposed by bacteria or eaten by other marine animals. The resistant, calcareous shell remains.
Embedding: The empty shell is quickly covered by fine sediment such as mud or sand. This rapid embedding is crucial to prevent destruction by currents or weathering.
Solidification and stone core formation: Over millions of years, more and more layers of sediment are deposited on the shell. Due to the high pressure and compression, the sediments solidify into rock (e.g. limestone). At the same time, mineral-rich water penetrates into the chambers of the shell and fills the cavities. These minerals harden and form a stone core or inner spout, which imitates the inner shape of the ammonite shell.
Dissolution of the shell: Over time, the original calcareous shell of the ammonite dissolves. What remains is the mineral stone core, which preserves the characteristic spiral shape of the ammonites. This stone core is what is usually found today as an ammonite fossil.
Here on the coast, you can find many such ammonites.
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Find an ammonite and measure its diameter as well as estimate its thickness.
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Describe in your own words how these ammonites came to the surface from the seabed.
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Include a photo in your log with yourself, your GPS device, or a personal item next to the object.
