problem with pool foundation

[PoolieQ]

When leveling the ground with a front end loader, we came to an area of grainy dirt with hundreds of rocks ranging from golfball to softball sized.
We had to dig about 2 feet down on one side to make it level. That's where hit the gravelly dirt. It's a 24 ft. pool and over half of the area is down to the rocky area. There seems to be no end to the rocks.
Any suggestions?

Thanks!