It takes about 25 minutes to dig a hole in the sand large enough to accommodate a man who is 5 feet 6 inches tall. Richard Gibson knows this because he has shoveled out what is called in the Marine Corps a "Ranger grave." The idea is that in lieu of barracks, you dig a hole until you can lie in it on your back, your nose beneath the ground, so that if a mortar explodes nearby, the shrapnel will explode overhead. The reality is that it's better to be lucky than a good digger.
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