Gravel that sinks is usually the base
I walked the side path in March and my boot went in. Two ruts ran the length of it, full of brown water, with the pretty stone gone. I had topped the gravel up in November. I topped it up again. By April the new bag was in the mud with the old one. I thought I needed more stone. I needed a base. The soil under the path was a sponge, and the gravel had been sitting on it like seed on a tray.
Gravel is a wearing surface. It is not a foundation. On a small UK plot a path still wants a compacted layer of hardcore or scalpings under the show stone, deep enough that a wet winter cannot punch through to earth. The base takes the boot and the barrow. The gravel only hides it and drains. Skip the base and every bag you pour becomes part of the soil. People blame the stone. The stone was doing a surface's job on dirt.
The edge holds what is left in. Path edging that lifts is usually the frost is that line. If the edge is out, the gravel spills and the ruts look worse. I do not reset an edge and call the path fixed. I scrape a test patch first. A fork and a spade are not the same digging tool. I use the spade to cut a small square and look. If I hit compacted stone in a couple of inches, I have a base that has thinned. If I hit wet earth, I never had one. The fork is for loosening a packed patch when I am rebuilding, not for stirring mud and hoping.
Depth is the other check. I would rather have a thin, even layer of gravel on a firm base than a deep drift on clay. A drift looks generous. It waves. It hides a hole. After rain you see the hole anyway. I also look at the soil under a soft spot. Black, wet, smearing clay will swallow stone forever. I would pull that out and put a base in, not feed it another bag. A membrane on mud is not a base. It stops weeds for a season and then it sits in a sag, holding water, with gravel sliding off it.
A raised bed that bows is usually the rails is the box beside the path. I would not use a bed wall as the only edge of a gravel run, and I would not tip path stone against those rails. Wet gravel piled on timber is a winter load those sides do not need. Gravel boards rot at the soil line is the same wet against a fence. Keep the path stone off the boards. The stain is the polite name.
Skip topping up as a habit. If you are buying a bag every spring, the base is the job. Skip decorative pebbles as the whole build. They roll, they never lock, and they vanish into clay. Skip a membrane laid on unlevel earth with a pretty bag on top. Skip building the path in a week of rain. You are compacting soup. Wait until the ground is just workable. Skip a wheelbarrow run on a path you have not given a base, then wondering why the ruts match the tyre.
This shows after winter, usually March, when the water has sat and the boots have been through. Autumn is when I would put a base in, or thicken one, before the wet months. I walk the path after the first long wet week of the year. If my heel sinks, I stop pouring bags. I scrape, I look, I decide whether I am standing on stone or on the plot.
I do not need a new kind of gravel because the old path sank. I need something under it that stays put when the soil is wet.
If I later add a buy link here, it will be a paid promo.