Originally Posted by creeper
Looks like a mole who didn't manage to excavate his tunnel quite deep enough
I had a similar first thought but it seems to be just the turf. I guess the mole could have moved just under the turfgrass. And moles are even more blind than most rodents and usually could not cut a line that straight unless up against a sidewalk edge or something.
You didn't have a leaking hose end herbicide sprayer leaking back on to a garden hose by chance? Or even a sprayer with a concentrated dose of Miracle Gro or some other fertilizer dripping down the hose?
You didn't leave a hose out on the turf by accident?