Characterization of Soils and Parent Material of the Arnott Moraine in Portage County, Wisconsin
File(s)
Date
1978-07Author
Nelson, John F.
Publisher
University of Wisconsin-Stevens Point, College of Natural Resources
Metadata
Show full item recordAbstract
The Arnott moraine is a landscape unit located four miles
east of Stevens Point in Portage County, Wisconsin. It is
a low ridge with 50 to 80 feet relief, is 1/2. mile wide,
and extends 18 miles in a north-south direction. The
purpose of this investigation is to study the soils and
geology of this landscape feature in order to evaluate two
theories regarding its origin. The two possible origins
are as follows; (1) it is an end moraine of early- or
pre-Wisconsinan glacial advance and is composed of glacial
drift (hence its name), or (2) it has weathered from granite
bedrock, is underlain by weathered residuum and has a
granite core.
Significant differences are apparent when topography,
drainage pattern, land use, and soil drainage characteristics
of the Arnott moraine are compared to those characteristics
of the Outer moraine, a Woodfordian end moraine located 2
miles east of the Arnott moraine. The Outer moraine has
steep, irregular slopes, many undrained depressions, and the
deranged or internal drainage pattern of a youthful
glacial landform. Many of the depressions are well drained
indicating the moraine is composed of permeable sandy
glacial drift.
The Arnott moraine has gentle, smooth slopes with a
well integrated drainage pattern characteristic of an
older landscape feature. The underlying materials are
dense and slowly permeable as indicated by the presence of
standing water in road ditches, a few shallow undrained
depressions, and a significant area of somewhat poorly
drained soils on the features gently sloping uplands.
Field investigations of soils and observations in 2
soil pits on the Arnott moraine revealed the presence of 2
or 3 different layers of materials in each soil profile.
The C horizon or parent material at each site was sandy
loam to loamy sand in texture and contained numerous
rounded erratics of gabbro and basalt which often had
pronounced weathering rinds.
Well drillers provided samples and logs for wells
drilled in the Arnott moraine. Materials penetrated by
these wells consisted of' 50 to 80 feet of dense loam underlain
by coarse sand and gravel considered to be glacial
outwash. Ice-wedge casts have been observed on the Arnott
moraine and are not found on the Outer or other Woodfordian
moraines to the east. This suggests the Arnott moraine was
ice-free and subjected to permafrost conditions before or
during the time when the Outer moraine was being deposited.
Based on the field observations and data from 1aboratory
analyses, the Arnott moraine is considered to be a
remnant of a moraine formed during an early-Wisconsinan
(Altonian) or pre-Wisconsinan (Illinoian) ice advance.
This landform was largely buried by the more recent advance
of-the Woodfordian age Green Hay lobe of the Wisconsinan
ice sheet. The small portion of this older moraine not
covered by deposits of the Green Bay lobe is the landscape
unit currently designated as the Arnott moraine.