This outcrop is part of the largest batholith of the Appalachian
mountain chain. The batholith is referred to as the South Mountain
Batholith (SMB). It has a volume of approximately 75,000
km3 of rock, and was emplaced approximately 380 million
years ago. Uplift, weathering and erosion are the mechanisms that
were responsible for exposing the large granite mass you see here
after it was emplaced several kilometres below the Earth’s surface.
The SMB contains the largest primary tin mine in North America near
Yarmouth.
The granite is highly fractured and jointed with cracks that
formed during the cooling of the bedrock. Glacial movement worked
to exaggerate these features and widened them by exploiting their
weaknesses and removing rock material. If you look closely at the
rock rubble at your feet you will find pieces of rock with purple
crystals. Don’t be fooled into thinking this is “Nova Scotia
Amethyst.” While Nova Scotia does have areas where amethyst can be
found, this is not one of them. You will also notice that this
purple mineral is found in lines or seams in the granite outcrop.
This purple mineral is fluorite (CaF2).
During the cooling of an igneous intrusion such as the SMB, some
materials precipitate and settle to the bottom of the intrusion.
After the granite became solid and cracks formed in it, some of the
material that settled to the bottom and was still in the liquid
form was able to ooze up through the cracks. The fluorite seams you
see here are examples of that oozing of liquid between the solid
masses of granite.
To claim this cache you need to send me an email with:
1. The answer to these questions (do NOT post answers
online):
a. Which is older the granite or the fluorite? Why?
b. What household substance do you think uses a derivative of
fluorite as one of its ingredients?
c. There are various types of granite, how would you describe this
particular granite outcrop (colour, etc.)?
2. Post a photo of you, your GPSr, and, if possible, a vein of
fluorite in the background.
You do not need to wait for me to accept your answers and photos
to post your find, but if you don't send me reasonable answers and
a photo, your entry may be removed from the listing. If there are
circumstances that prevent you from doing some of the above
requirements, let me know and I'll consider them on an individual
basis.