Dirt lifting up between rocks.

[Joe777]

I purchased this home that has quite a mess of rocks and landscaping.
I'm considering just removing all the rocks and putting down grass.
This morning I found that dirt had rose up between the rocks that wasn't there the night before and I can't explain why this is happening or if this will be an issue when I take the stones off and lay down sod.
Any ideas why this is happening? or could this be a more serious underlining issue? Animals?
See pics:

Pic1

Pic2

[gumbo2176]

Looks to me like you have some sort of burrowing mammal making your pathway a home. Lift up the stones near the upheaved dirt and see if you can find a tunnel.

[imafan26]

Actually, it looks like it was a nice paver patio at one time. I would save the pavers, if not for a patio, you could still use them for a pathway.

If the dirt is coming up overnight, then it probably is something living underground.

[MoonShadows]

Yes, most definitely. Save them for a garden path. That's what we did. We just put down an inch or so of screenings (rock dust) and dropped the slates down.

[applestar]

The animal could just be moles — earthworms congregate under hardscape when it gets cold because of the thermal mass and moles follow. I consider moles one of the good guys and don’t begrudge them the plentiful earthworms.

BTW, I would just pull out the grass and weeds and plant herbs between the rocks. Depending on your climate, creeping steppables like creeping thyme, marjoram, rosemary or oregano would be some good choices. Also, micro-leafed basil, pennyroyal, or sedum, creeping phlox, sweet alyssum, ... etc. If the area is currently very weedy, then it might be safe enough to plant edibles. I would be leery of planting edibles if the area is clear of growths and dead beyond normal winter dearth.

Weeds are easiest to pull when ground is soaked.