Located just northeast of Jackson, the Phyllis Haehnle Memorial
Sanctuary has long been a favorite spot for avid birders, who flock
to this Michigan Audubon Society nature area to view the populous
sandhill cranes as well as the thrushes, chickadees, woodpeckers,
warblers, egrets, and other birds that nest or winter here.
However, this sanctuary is much more than a haven for feathered
friends; its 1.2-mile nature trail offers visitors the opportunity
to learn about the ecology and geology found on this 900-acre
property.
Most of Michigan's topographical features were created by the
glaciers that covered not only the state but most of the northern
part of the United States. These huge sheets of ice —
thousands of feet thick — scored and gouged the surface of
the land as they advanced and deposited tons of rock and soil as
they retreated. The Great Lakes owe their existence to the
sculpting action of the glaciers, as do many of the ponds, lakes,
and other water features throughout Michigan. Similarly, the
fertile soil that serves as the foundation for Michigan farmlands
can trace its origin to the glacial till left behind by the melting
ice sheets, while the many cobbles and boulders found on farmlands
and in forests have traveled to their current locations via glacial
transport,
Near the Observation Hill bird-viewing area and along the nature
trail (look for wooden signpost #2), you will see many examples of
these glacially transported boulders. Called glacial
erratics because their mineral make-up does not match that of
the area where they are found, these rocks are typically rounded
due to the wear and tear experienced during their icy ride. Smaller
erratic rocks, or cobbles (less than 12 inches in diameter) can be
found tucked into the woods and in some of the fields of the
sanctuary, piled up into stone fences by the farmers who once
worked the land here.
Further down the nature trail near wooden signpost #5, Eagle
Lake presents itself as a stunning example of glacial water works.
Glaciers created lakes and ponds in three typical ways:
by scouring a depression out of the bedrock over which the
glacier was passing;
by depositing glacial drift (loose rocks and soil) in a manner
that dammed an existing river or stream;
by calving, or leaving large chunks of ice behind, covered with
glacial drift. In the latter case, when the left-behind iceberg
melted, it created a pocket in the land which filled with meltwater
to form a lake.
In order to obtain credit for visiting this Earthcache, please
email us the responses to the following questions:
The text "GC2GN17 — Haehnle Sanctuary" at the top of your
message
1. Go to Eagle Lake (coordinates are N 42º 19.547, W 84º 17.357).
Examine the lake and its shoreline carefully. By which of the three
glacial processes listed above do you think this lake was created
and why? Explain why Eagle Lake was not created by the other
two processes; include your observations to back up your
theories.
2. Examine the soil on the shores of Eagle Lake and slightly
uphill from the water (use gloves if you don't wish to get your
hands and/or fingernails dirty). Is the soil silty, more clay-like,
or a combination of silt and rock fragments. Taking into account
the glacial nature of the area, why do you suppose the soil
composition is this way?
3. Next, head to the glacial erratic at Observation Hill
(coordinates are N 42º 19.328, W 84º 17.259). Examine the erratic
carefully. How many kinds of minerals you can easily identify with
the naked eye? If possible, identify these minerals.
4. From the Observation Hill erratic, follow the grassy trail
towards the far parking lot. Just a few feet on the other side of
the nature trail's trailhead is a grouping of more glacial erratic
boulders. How many boulders are grouped here? Compare this grouping
of erratics with that at wooden signpost #2. How did these boulders
end up grouped the way they are?
Optional: Post a photo of you or your GPSr with the
Haehnle Sanctuary erratic with the inset brass plaque. Even better:
if you complete this Earthcache in October or November, a photo of
you or your GPSr with the cranes in the background!
Please do not log this Earthcache as found
until you have received approval of your emailed responses to the
additional logging requirements. Once you have received our email
approving your responses, you may go ahead and log your find. Those
who submit incorrect responses will be given two weeks to submit
the correct responses before their log is deleted. Those who log
this Earthcache as found without submitting the additional logging
requirements will have their logs deleted within 24
hours.
Thank you for coming to our Earthcache at the Phyllis Haehnle
Memorial Sanctuary! Enjoy your visit, and please remember that this
is a nature sanctuary, so avoid disturbing the wildlife you'll
undoubtedly encounter here.
Congratulations to geo_string,
the First to Complete our Earthcache!
Placement approved by
the Phyllis Haehnle Memorial Sanctuary and the Jackson
Audubon Society.