Here's why:
* Terrane Accretion: This process involves smaller landmasses (terranes) colliding with and attaching to a larger continental plate.
* Accretionary Wedge Formation: As the terrane collides, the oceanic crust and sediments on its leading edge are scraped off and piled up along the edge of the continent. This creates a wedge-shaped pile of deformed rock and sediment, which we call an accretionary wedge.
Key Characteristics of Accretionary Wedges:
* Folded and Faulted: Intense pressure from the collision causes the rocks in the wedge to fold and fault, creating a complex structure.
* Metamorphic Rocks: Heat and pressure during the collision process can transform sedimentary rocks into metamorphic rocks.
* Volcanic Activity: Accretionary wedges are often associated with volcanic activity as the subducting plate melts and generates magma.
* Examples: The Coast Mountains of British Columbia and the Appalachian Mountains in the eastern United States are examples of mountain ranges formed by terrane accretion.
Let me know if you'd like to delve deeper into any of these aspects!
