Answer:
Syncline is the answer to this.
Step-by-step explanation:
Syncline is a rock layer arching downward towards the inside layers of the Earth. The opposite of a Syncline is an anticline. Which is the rock layer arching upwards. Synclines are like mountains underneath Earths surface. Anticlines are just mountains above the surface that people walk and hike today. Synclines are formed when tectonic plates move toward each other, compressing the crust and forcing it upward.
Hope this helped you!