[Image: Close-up of the 2010 State Geologic Map of California].

An interesting story published last month in the L.A. Times explored the so-called ?sweet spot? for digging tunnels along the California/Mexico border.

?Go too far west,? reporter Jason Song explained, ?and the ground will be sandy and potentially soggy from the water of the Pacific Ocean. That could lead to flooding, which wouldn?t be good for the drug business. Too far east and you?ll hit a dead end of hard mountain rock.?

However, Song continues, ?in a strip of land that runs between roughly the Tijuana airport and the Otay Mesa neighborhood in San Diego, there?s a sweet spot of sandstone and volcanic ash that isn?t as damp as the oceanic earth and not as unyielding as stone.?
More accurately speaking, then, it is less a sweet spot than it is a soft one, a location of potential porosity where two nations await subterranean connection. It is all a question of geology, in other words?or the drug tunnel as landscape design operation.

[Image: Nogales/Nogales, via Google Maps].

With the very obvious caveat that this next article is set along the Arizona/Mexico border, and not in the San Diego neighborhood of Otay Mesa, it is nonetheless worth drawing attention back to an interesting article by Adam Higginbotham, written in 2012 for Bloomberg, called ?The Narco Tunnels of Nogales.?

There, Higginbotham describes a world of abandoned hotel rooms in Mexico linked, by tunnel, to parking spots in t...