The (pure?) sulfate they just drilled is much more than just a crust...
This nodular layer has some thickness to it, and some weak layering. Of course, this could be aeolian or fluvial deposits from a significant interlude. This layer also has nodules that look like they may be malformed or eroded blueberries, more so than was seen at the bread loaf rocks. I will try to find one of the Spirit pics that reminded me of pillow basalt.