Physical Changes:
* Heat and Pressure: The intense heat and pressure involved in metamorphism can distort, deform, or even obliterate the fossil. The original shape and details of the fossil can be significantly altered or even completely destroyed.
* Recrystallization: Minerals within the fossil and the surrounding rock recrystallize, changing their structure and composition. This can make the fossil harder, more brittle, and less recognizable.
* Compression: The pressure can compress the fossil, flattening it and reducing its size.
Chemical Changes:
* Mineral Transformation: The minerals that make up the fossil can transform into different minerals. This can affect the color, texture, and chemical composition of the fossil.
* Dissolution and Replacment: Some minerals in the fossil may dissolve, while others may be replaced by new minerals. This can create a "ghost" of the original fossil, where its shape is preserved, but the original material is gone.
Overall Impact:
The severity of these changes depends on the intensity and duration of the metamorphic process. In some cases, fossils can survive metamorphism with minimal alteration, especially if the metamorphic event is relatively low grade. However, in high-grade metamorphism, fossils are often completely destroyed or become unrecognizable.
Examples:
* Fossil Shells: Shells in limestone can be recrystallized into marble, often losing their original details.
* Fossil Bones: Bones can become compressed and flattened, or even dissolve entirely.
* Fossil Tracks: Footprints can be distorted by heat and pressure, making them difficult to identify.
In Summary:
Metamorphism can have a significant impact on fossils, often altering or destroying them. The level of change depends on the intensity and duration of the metamorphic process. While some fossils can survive with minimal changes, high-grade metamorphism can often lead to complete destruction or unrecognizable remnants.
