Imagine that you are a member of a team of scientists who are drilling into a large crater approximately 200 km wide. The crater
was formed by an NEO impact that wiped out many species 251 million years ago. The drilling team will recover rock samples during the drilling process. You have some data to suggest that the crater is located between 500 and 1,500 meters below the surface. How will the drilling team know when the drill reaches the crater
The team will obviously known that they have reach the crater because during impact the rock would have ungergone contact melting of the rock. However, the rock maybe composed of angular fragments in a matrix that may be similar or a different material underneath the crater. Suppose the scientist drilling further down the surface, there will be presence of little or no impact. But inside the crater there will be fragments of broken rocks. They will observe the shocked minerals and the drill will eventually located the undisturbed sequence of rocks at the crater floor.
The oceanic crust is forced under the continental crust and into the mantle. Crompression causes mountains to form on the continental crust. Material in the mantle melts as volatiles seep out of the oceanic crust. The molten material rises to the surface, forming a continental volcanic arc.
