and they don't simply drill a borehole like we do because???
An obvious guess might be that it takes a machine to bore a hole vertically, but with enough slaves you can dig horizontally by hand. Bedrock don't dig real good, topsoil's much easier...
9 posted on 02/04/2013 6:34:53 PM PST by ZOOKER
( Exploring the fine line between cynicism and outright depression)