2D Terrain Collision Detection

I am messing around with a project, built in the style of a 2D side-scroller game.

The ground will eventually look something similar to this:

https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQM0ZuDsGAhtcVtvuacBfcYdppdSg438k5GHFY3vgI3OcP2QTpkHA

What is my best course of action for collision detection assuming the only data I’ll have are the 2D Vector coordinates of each vertex on the terrain?