I have an area between our house and our neighbour's. It's about 12' wide. No grass grows here and it's always moist and damp. We want to put down some type of pathway. It won't be walked on much because we have interlock on the other sides where there's a gate. This side is just to clean up the area and to walk on only occasionally. What can we use as the ground cover? The two options we're looking at is 3/4" riverstone or black marble chips. THe marble chips are 4 times as expensive. What are the pros and cons of the two? Of course the black marble looks better, but besides that, any reason to spend 4 times the price? Note that the area is quite visible because it's beside both our front porches.