It all pretty much says Mars was a place, particularly early in time, where liquid water was abundant at or close to the surface.

The rocks in the Columbia Hills are nothing like the basalt on the plains. Water was involved in practically every one that we've seen so far.

The rocks in the Columbia Hills are nothing like the basalt on the plains, ... Water was involved in practically every one that we've seen so far.

Water was involved in practically every one we have seen so far.

We're finding abundant evidence for alteration of rocks in a water environment.

We're finding abundant evidence for alteration of rocks in a water environment. What we want to do is figure out which layers were on top of which other layers. To do that it has been helpful to keep climbing for good views of how the layers are tilted to varying degrees. Understanding the sequence of layers is equivalent to having a deep drill core from drilling beneath the plains.