Here's depth to bedrock in Missouri. Red = farther down, green = closer to surface. This way it can be very clearly seen where the glaciated area ends and where the karst area begins. I imagine prior to glaciation this may have been a single unified landscape all the way up to the Driftless Area in Wisconsin and perhaps farther.
It's always nice to know the geological history of your local area and to know from which era the nearby mountain range is etc.. but I think in general I'm more interested in what's going on on top of the surface.
Geology was my minor subject during the Bachelor, interpreting geological maps and hydrogeology was cool, though I sucked at identifying rocks and minerals