Foil: Verb
1.To prevent (something) from being accomplished.
2.To prevent (someone) from accomplishing something
One of the senses of the noun foil has to do with a sport. Look for the two nearby caches that have that sport mentioned in their names. The northernmost cache will be referred to as "Cache A", while the southernmost will be "Cache B".
North: Subtract the north coordinates of "Cache B" from the north coordinates of "Cache A", then subract 3 from that. Take this result and subtract it from the north coordinates of "Cache B".
West: Take the minutes of the North coordinates from either cache and remove everything after the decimal (should be a 2 digit number). Subtract this from the west coordinates of "Cache A"
You are looking for a tiny cache, bigger than a nano but smaller than a bison tube. I was unable to get great satellites in the area, so if your coordinates take you to a beaver stump, just go about 10 feet north.