Sieur de LaSalle
A quick 2 stage Multi-Cache. The first stage will take you to a plaque. The final is a Bison Tube. There are two dates on this plaque.
Take the first date to appear, divide by 1000, (you will get X.XXX) then add it to the following meaningless North Coordinates N 43 16.438
Take the second date to appear, divide by 1000, (you will get Y.YYY) then subtract it from the following meaningless West Coordinates W 079 52.977