Citing everything from bedrock depth to soil chemistry, experts say building a wall spanning the 2,000-mile border will be much tougher than erecting one of Trump's trademark skyscrapers.
“Earth doesn’t forgive sloppy,” field geologist Mika McKinnon warned in a tweet following Trump’s directive last month to design and construct the wall.
The southern border between the U.S. and Mexico is made up of wetlands, grasslands, desert, rivers, mountains and forests – all of which could pose pitfalls for builders.
Swaths of the area also feature a thick layer of loose sediment – like dirt, sand and soil – on top. Some spots are packed with hydrophilic clay soil, which swells, moves and could destroy the foundation.