I think it's a case of "the right tool for the job". Shovels are fine for moving or turning soil, but not so good for rocks.
I was lucky to be living in a place with some abandoned sheds, so I poked around and found an abandoned pick-head, rusty and ancient. I out a wood handle on it and the rust came right off as I used it!
The pointy end does a great job if you hit right between 2-3 rocks, then use it as a lever. The weight sure does make it hard to lift and swing, but when it hits, those rocks do MOVE.
The fatter end is good for clay that's at least a little softer than rocks. It still sinks in, but when you lever it, you break free a wider swath of clay, or clay and gravel.
shovels for soil
picks for rocky soil
mattocks for soil + roots
Trying to use a pick when there are tough, tangled roots is almost impossible. Roots can be tougher than rocks to lever out, and somehow they grab the pick and pull back! I have to bend over and pull the pick out straight. You NEED a mattock to cut tough roots.
When I dig out the below-grade foundation of a raised / sunken bed, sometimes it's a three-step process.
1. Use the pick to break up what I can, levering out rocks and breaking the clay/rock mix.
Use the pick to expose the root layer.
2. Use the mattock to cut the roots. When i start to hit more rocks, trade the mattock back for the pick, to pry the rocks away from the roots. Use the mattock to cut more roots and expose more rocks.
3. Step three is ongoing as I use pick and mattock to break things loose. I use a hoe or steel rake to pull loose chunks away from the work area and make a pile big enough to be worth shoveling into a wheelbarrow.
P.S. Once you dig below grade in impervious soil, you need to assure drainage, or the hole will become a mud wallow or pool. I use both ends of the pick, and usually the mattock blade, to cut a narrow slit trench down from the lowest point of the bed's foundation to a some point that is even lower.
My caly is hard enoguh that I don't even have to back-fill the slit trench with gravel or drainage pipe. The walls are like concrete. Of course, if you step into it wrong, it's an ankle-breaker.
It's probably smarter to just ignore soil this bad, treat it as bare rock or concrete,and just build up raised beds with purchased soil or soil that's 60-80% amendments. But "cultivating the soil" is my favorite part of gardening, so I found the tools I needed. Most of my beds go down as well as up.
