Wisconsin DNR contributed $12,600 and NWS
members contributed some $8,906 towards the
approximate $33,000 project. Julie Hein-Frank was the
project leader, handling the design and procurement
and supervising the installation; she personally raised
much of the remaining funds from foundations and
local clubs/associations. NWS handled all of the cash
flow, bill payments etc.
Errors and Misconceptions about Door County
Geology (an Editorial continued)
Allan F. Schneider
Several common errors that pertain to the names and
altitudes of lake phases that occupied the Lake
Michigan and Green Bay basins during late-glacial and
postglacial time were perpetuated for years in our
state park newspapers and trail brochures, including
those for Potawatomi, Peninsula, and Newport State
Parks. Gene Tiser, the District Naturalist of the former
Lake Michigan District, and I were reasonably
successful in correcting most of these items several
years ago. However, some of these errors and
misconceptions continue to persist. .
Lake Nipissing, for example, is commonly referred to
as “Glacial Lake Nipissing” (or “glacial Lake Nipissing”),
as it was in earlier editions of the Newport State Park
Visitor and other state park newspapers. Lake
Nipissing was, in fact, a postglacial lake that occupied
the Lake Michigan and Lake Huron basins beginning
about 5,000 years ago; glacier ice had left the Lake
Michigan and Green Bay basins more than 5,000 years
earlier. Thus, it is inappropriate and misleading to
refer to the lake as “glacial Lake Nipissing.” Remains of
the Nipissing shoreline may be seen at several places
in Newport State Park, but probably the best remnant
is a wave-cut bedrock bluff along Lynd Point Trail a
short distance west of Lynd Point.
Lake Algonquin, on the other hand, was a glacial lake
and may properly be designated as “glacial Lake
Algonquin.” However, the level of Lake Algonquin was
never 60 feet above the present level of Lake Michigan,
as commonly stated – as it was, for example, on former
trail marker M-17 (now post 8) of Meadow (or Upland)
Trail. The level of glacial Lake Algonquin was only
about 25 feet above modern lake level – the elevation
of the outlet of that lake at Chicago. Shoreline deposits
of that old lake are now about 650 feet above sea level
in Newport State Park, the shoreline having been
uplifted 40-45 feet as a result of isostatic rebound
during and following deglaciation. (Isostatic rebound
refers to uplift of the earth’s crust, which was
depressed due to the weight of glacier ice.) Beach
deposits of glacial Lake Algonquin can be examined in
the old gravel pit on the east side of County NP a short
distance north of the park entrance.
About 10 years ago, a free trifold was distributed to
hikers at Potawatomi State Park to help identify
features at 14 numbered signposts along the “Ancient
Shoreline Trail.” It referred to Lake Nipissing as both
“Glacial Lake Nipissing” and “post-glacial Lake
Nipissing.” It stated (1) that the Nipissing shoreline is
60 feet (25 feet) above present-day lake level, (2) that
the glacial hills in the park were shaped by glaciers 1-2
million (18-20 thousand) years ago, (3) that glacial
erratics were left behind by glacial meltwaters (glacial
ice), and (4) that the bluffs in the park are the eastern
(western) edge of Silurian-age bedrock. When I called
attention to these errors, the trifold was withdrawn.
Another common misconception about the geology of
Door County relates to the definition of soil and
references to the county’s “thin soils” or “shallow soils”
as those terms are used, for example, in the attractive
little booklet titled “Protect the Water You Drink.” (I
really like the content of this wonderfully informative
booklet. All Door County residents should read it.)
If one follows the engineer’s general concept of soil,
which many geologists do, as all unconsolidated
material above bedrock, then references to the
county’s “thin soils” are absolutely correct. However,
that concept of soil is not the common usage or
definition of soil employed by soil scientists and most
geologists. While it is true that Door County soils are
relatively thin, it is not really “thin soils” that relate to
our serious water pollution problems in parts of the
county, but rather the absence or virtual absence of
glacial deposits, which serve as parent materials from
which most of our soils are developed. Throughout
much of northern Door, glacial sediments are less than
5 feet thick and in many places bedrock occurs right at
the surface. Therefore, I suggest that the use of “thin
glacial deposits” is preferable to “thin soils” if
confusion is to be avoided.
LAKE MICHIGAN WATER LEVEL
As of September 9th Lake Michigan average water level
was at 577.95 feet, which is above the chart datum but
four inches below August 9th and considerably below
the highest monthly average of record.