[templar]

All landers so far have deliberately landed miles and miles from anywhere that wasn't almost perfectly flat, for that reason.

Yeah, I realize that. I was wondering how all those rocks got scattered all over the place in the plains. I would expect them around the lower plains of mountainous areas, but what carried them into the plains? Glaciers? I'm quite uninformed on geology.

[John H K]

There's a very large channel that appears to be water carved, by a sudden flood(or more than one flood) leading from a high area down into Gusev crater.

Material could have been transported by water down that channel from elsewhere.

But, as mentioned, you can also get rocks from debris from large meteorite or asteroid hits, etc. There's more of that on the Moon, Mars, etc. than on Earth.