Here's why:
* Contact Metamorphism: This type of metamorphism occurs when hot magma or lava comes into contact with existing rocks. The heat and chemical reactions alter the original rock's texture and mineralogy.
* Sandstone and Shale: Sandstone is composed primarily of quartz grains, while shale is made up of clay minerals.
* Hornfels: This is a hard, fine-grained metamorphic rock that forms from the contact metamorphism of various sedimentary rocks, including sandstone and shale. The heat and pressure cause the original minerals to recrystallize into smaller, more compact grains, creating a dense and often dark-colored rock.
The Palisades Sill is a large igneous intrusion in the New Jersey area. Its heat significantly altered the surrounding sedimentary rocks, transforming them into hornfels.
