Find the stones in the far corners,
Northwest / Southwest / Southeast / Northeast
Here is where you will find the cache
N 50 A B . C D E W 98 V W . X Y Z
You will need to look at the dates on these stones and input the specified numbers in the place of the coordinate letters
At the Northwest location you will need the second number for V, and the sixth number for Y.
At the Southwest location you will need the sixth number for B.
At the Southeast location you will need the fourth number for X and for Z, also the seventh number for C, and the twelfth number for D.
At the Northeast location you will need the sixth number for A, the tenth number for E, and the fifteenth number for W.