Consisting of or resembling shale, a kind of rock that breaks easily into thin layers.
The word 'shaly' makes people think of rocks, layers, and maybe digging.
Examples:
The ground is shaly and breaks into pieces.
The shaly rock is easy to break.
We found a shaly hill near the river.
The shaly ground is like a big cookie!
The shaly mountain is as thin as paper.
The shaly ground is like a puzzle, easy to break into pieces.