It may be a dry creek bed that was landscaped in for drainage/erosion problems. If so, it probably channels water and doesn't allow time for Round-Up, or bleach, etc. to soak down underneath and truly kill the grass from the root.
Is it possible to remove the rock, spray, and cover back up?

Noxall.

Yarddog - No, it's definitely not a dry creek bed. How do I explain it? It's just the side extensions of the house (leading from the backyard to the front) that are in between our house, and the fence. And on the other side of the fence the neighbors have the same thing. I would imagine they put rocks down because the rain falls off the roof in those spots and pools, never dries because no sun gets back there, and just leads to weeds aplenty. Nowhere near a spot where a creek would even think about being, we're talking northwest Oklahoma here. Creeks are non-existent.

Not possible to remove, we're talking 400-500sq feet of rock here. My back aches at the thought.

I'll check out Noxall, thanks gsweater.

Do you think I was suggesting that there used to be a creek running through your property?
"Landscaped" in, meaning it was a rock bed placed there to channel water that was either pooling or eroding the soil (exactly what you're describing).
Good luck with the Noxall. I've had one of these before, gasoline didn't even do the trick.

While Noxall doesn't work forever, it's by far the best product I've found for long term control of weeds and grasses. Pretty close to a full year for me. I apply it in February here, but may vary where you live.

I use it in my gravel driveway and along all the garden paths with stone mulch. I'd say in the driveway, which at one point was covered with grass and sedge, I spot spray twice a year - it's completely clear and looks like brand new gravel almost year round. Just a few making it through. Probably unnoticeable to anyone else, but I'm always on the lookout for weeds lol.

Where my driveway goes to the back of the house, it's on a slope, and that's really the only area where I seem to concentrate with spot spraying (likely that rain is washing it down the slope a bit). On the flat part, it's clear and have very little to spray there. My gravel paths need no spot spraying.

Just be careful when applying because if there is any overspread, it can kill your desirable plants. In tight quarters, I do it by hand.

This post was edited by gsweater on Mon, Jun 10, 13 at 21:44

Awesome, thank you gsweater!