The annual gathering. - OR -
Why am I not gardening in a hole? I seem to throw out 2 gallons of cobbles on an annual basis, yet the garden gets no lower. Must be added humus.
I really must introduce you to "Uncle Stan" one of these days, then what I'm about to say may make more sense.
I was about to say that the largest, visible, stone came up from a depth of less than Uncle Stan.
ALL shall be revealed - in the fullness of time.