The cache is not located at the listed coordinates. Rather they take you near the residence of a famous individual. Here you must observe the street number of the residence and apply it to locate the picnic area.
Given the location of the picnic area as N42 30.A0B W070 49.9CD and the street number as E,F,G, solve the following to find the picnic area:
A = F plus 1
B = E plus 1
C = E plus F plus 1
D = E plus F
After you have enjoyed a leisure lunch and taken in the fabulous view you can wander around and find the answers to the questions presented below.
The location of the cache is at the following coordinates:
Latitude N42 30.HIJ and Longitude W070 50.KLM
The six missing numbers can be determined by solving the following questions:
H - When did the town purchase this land? Add the last two numbers and subtract the sum from the second number.
I - When was a generous donation made that allowed the transfer of this land? Subtract the last number from the second number.
J - When were the quarters razed? Add the first and third numbers and subtract the sum from the last number.
For Longitude:
K - When did the town petition Congress? Use the last number.
L - In what year did WWII impact this area? Subtract the sum of the first and last numbers from the third number to solve for "L."
M - And now the spoiler (change location). In what year was this area presented to the town of Marblehead? Add the first two numbers. Now subtract this sum from the sum of the last two numbers to determine the value of "M."
You should now be able to proceed to GZ and find the cache.
In recognition of successfully completing the search for this cache, the FTF will be rewarded with a $1 gold coin commemorating Sacajawea, the young woman who served as translator, peacemaker, caretaker and guide, thus making possible the historic journey of Lewis and Clark in the early 1800's.
FTF honors and the gold coin go to BUGEYE59.
You can check your answers for this puzzle on GeoChecker.com.