At those coords on the trail you see a brown basalt boulder.
Where did it come? How did it get here among all these grey rocks?
After all, the nearest basalt bedrock is three miles away
(to the northwest).
During the last ice age, daily melting would refreeze at night,
grabbing rock fragments which would then be carried along with the
glacier. Ultimately, they were left here, worn round from their
long journey. They are called erratics.
Continue to 41 25.696 / 73 12.413, you'll see more basalt
erratics on your way. Once there notice the lighter colored
pegmatite erratic on the left (northwest) with it's
crystals. Pegmatite forms from molten rock far below the surface
and cools more slowly, resulting in large white or pink crystal
intrusions.
You will be near a small stream when you arrive at 41 25.980 /
73 12.700 where you'll see gneiss (pronounced "nice")
boulders. They appear black with white banding. Originally basalt
when this area was covered by ocean ages ago, heat and pressure
changed them to what you see now--a type of metamorphic
rock.
Now head to one of the overlook trails and find what looks like
a "stone step" by 41 25.675 / 73 12.730. What are those hard dark
reddish lumps sticking up from it? Garnets. Harder than the
stone they are embedded in, they survive rain, wind, ice and your
shoes as the surrounding rock gets eroded away.
So ends the first part of our adventure... Now to claim your
find, head over to the trailhead of Pomperaug: 41 25.714 / 73
12.232 (hike or drive to pull-off parking) or the upper camping
area trailhead 41 25.356 / 73 12.200 (park at the station and walk
up the road unless camping or invited guest) and hunt for the
answers!
IMPORTANT:
Click here to email the answers to the following
questions when you submit your log (do NOT put in your log even
encrypted):
- What could, 41 25.075 / 73 12.000 this area be called?
- Along the trail at: 41 25.118 / 73 12.009, do you find basalt,
garnets, gneiss or pegmatite?
- At this location: 41 25.455 / 73 12.100, which rocks are
these?
In your online log feel free to answer the following:
What is the most interesting thing you learned from this
cache?
How many people were in your group? Ages?
Glossary:
basalt; the dark, dense, igneous rock of a lava flow
bedrock; unbroken solid rock below soil
erratic; wandering, not fixed
erode; eat away, disintegrate
garnet; hard pink, red, brown or green gems
gneiss; metamorphic rock with bands of different color
(pronounced "nice")
igneous; rock that was molten
intrusion; injection of molten rock
metamorphic; exhibiting profound change
pegmatite; coarse crystalline igneous rock
For more details:
CT DEP Kettletown Geology