Based on the cross-cutting nature of contact metamorphism, how could you tell whether a basalt layer between two shale beds was a lava flow or a sill?
a. if it was a lava flow, the basalt would be metamorphosed into slate along its edges
b. if it was a sill, the basalt would be metamorphosed into slate along the edges.
c. if it was a sill, both shale beds would be metamorphosed where they came in contact with the basalt