This is not your typical
geocache-it is an earthcache. You will not find a "cache
container" at the listed coordinates. An earthcache is
designed to bring you to a geological feature and educate you. Of
course, as with any geocache you can earn a "find" if you
complete the requirements listed at the bottom of the
page.
OVERVIEW
Rich tamarack swamp is a groundwater-influenced, minerotrophic,
forested wetland dominated by the tamarack tree (Larix
laricina) that occurs on deep organic soils predominantly in
central and southeastern Wisconsin. See the State diagram.
Ground-influenced means tamarack swamp are typically fed by
groundwater. Minerotrophic refers to the fact that the
groundwater supplying the swamp is a laden with minerals like
calcium and magnesium.
TOPOGRAPHY
The effects of the
advancing and retreating glaciers can be seen in the headlands of
Cape Cod, the Finger Lakes of New York, and the hills of Michigan,
but nowhere is the glacier's mark upon the land more impressive
than in Wisconsin.The
last glacier in Wisconsin ended 10,000 to 15,000 years ago.
Glaciers produced much of the landscape in Wisconsin including the
tamarack swamp in Menomonee Falls. Rich tamarack swamps occur in
drainage channels, outwash plains, and kettle depressions formed
from a rapidly receding glacier. See the
diagram of a
glacier's edge below. Drainage channels are rivers of water and
sediment formed by the melting ice. The outwash plain contains
glacial sediments from the drainage channel. Lastly, as the glacier
retreats it may also leave huge pieces of itself behind. These ice
blocks left may be many hectares in diameter. As the blocks
melt they form a depressions in the earth called kettles. See the
diagram below.
The tamarack swamp is
often found where groundwater seeps occur at the bases of moraines.
Moraines are deposits of soil left behind at the edges of the
glacier; they often form ridges or rolling hills. Rich tamarack
swamps typically occur in association with headwater streams and
adjacent to inland lakes. However, the one here in Menomonee Falls
does not. As you drive around the tamarack swamp here, it is clear
the entire swamp lies in a gentle depression.
SOIL TYPE
The organic (being composed of decayed plant material) soils
underlying rich tamarack swamp are typically comprised of peat
mosses containing large amounts of woody debris and occasionally
layers of grass or rush-dominated peat. The soil profile often
contains or is underlain by marl, a calcium carbonate precipitate
that accumulates as sediment in shallow lake bottoms. Sediments
deposited by the glacier in southern Wisconsin are typically high
in calcium and magnesium. The groundwater flowing through these
sediments becomes laden with these minerals and is termed
minerotrophic. As a result, groundwater discharge into rich
tamarack swamp has high levels of alkalinity and dissolved calcium
and magnesium carbonates.
Due to anaerobic (oxygen lacking) conditions associated with the
intermittent high water table and organic soils, trees growing in
rich tamarack swamps are often shallowly rooted, making them
susceptible to falling in the wind. Thus, it is normal to see many
downed trees.
NATURAL PROCESSES
Due to the strong influence of groundwater, water levels in rich
tamarack swamps tend to fluctuate less than in many other wetland
types. Although rich tamarack swamp is partly groundwater fed,
seasonal water-level fluctuations are common with water levels
highest in spring and lowest in late summer and fall. The
Menomonee Falls tamarack swamp is typically quite dry in the late
summer and fall so that you can easily walk into most of the swamp
without getting wet.
THREATS
Protecting the hydrology (movement of water) of rich tamarack
swamp is critical for its continued existence and may include
avoiding surface water inputs to the community from drainage
ditches and agricultural fields, clearing blocked road culverts,
which can cause prolonged flooding, and maintaining native
vegetation types in the uplands surrounding the community.
LOGGING THIS
EARTHCACHE
In order to log this earthcache you must
complete task number one:
1. Email me the answers to
these questions:
a. What does the term
minerotrophic mean?
b. Tamarack swamps
typically occur in what three types of glacial formations?
c. Is this tamarack swamp
alkaline or acidic?
d. Does the water level in
the Menomonee Falls tamarack swamp remain static year round?
2. Optional: Take a self photo
with your GPS or your team with a GPS at ground zero with
the tamarack swamp in the background. Then post the photo with your
log. Try to get at least one person and a GPS in the photo. See
the previously posted photos! If you are geocaching alone, hold you
camera at arms length to take a self photo, please.
Failure to complete task number one as
listed above (emailing the answers) will result in log deletion
without notice.
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