I grew up in the hill country of Texas, on the Edwards Aquifer. The limestone there is like swiss cheese. I've never understood the 'erosion' theory regarding how there could be so many tubes riddled throughout the hill country aquifer range if it was erosion. Erosion would wear grooves, not small tunnels zig-zagging all over. It couldn't have *formed* like that from sedimentary deposition for crying out loud...
So what's that leave? The answer I think is quick shocking!
"I have no fear to shout out my ignorance and let the Wise correct me, for every instance of such narrows the gulf between them and me." -- Michael A. Harrington