Table Name |
Field Name |
Begin Column |
Definition |
Valid Values |
Descriptions |
Millsgp.dbf |
Sgpot_id |
|
Number, 4 |
e.g., 100-999 |
Unique identifier for
the field-mapping units. |
|
Sediment |
|
Text, 50 |
e.g., Alluvium; Bedrock
Outcrop; Patchy Silt, Sand, Gravel over Till; Clay, Silt, and Sand; Sand and
Gravel; see below text values and their descriptions for information that
will help discern each description which may contain multiple of these values |
General description of
the dominant sediment material for each mapping unit. |
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Alluvium |
Sediment deposited by a
river or stream. Contains sediment
particles ranging from clay, silt, sand, and gravel. |
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Bedrock Outcrop |
Exposure of bedrock |
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Clay |
Clay is very
fine-grained sediment that is less than.0.004 mm in size. |
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Gravel |
Rock fragments of
specific particle size that is larger than 2 mm and less than 63 mm. |
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Organics |
Soil that contains
decaying organic matter. |
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Sand |
Rock fragments that
range in diameter from 0.0625 to 2 mm. |
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Sand with Gravel |
Sediment that contains a
mixture of rocks in varying sizes ranging from 0.0625 to 64 mm. This description is given to sediment
that contains less than 15% by volume gravel. |
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Sand and Gravel |
Sediment that contains a
mixture of rocks in varying sizes ranging from 0.0625 to 64 mm. This description is given to sediment
that contains greater than 15% by volume gravel. |
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Silt |
Rock fragments that
have a diameter between 0.004 to 0.0625 mm. |
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Till |
A term used to describe
the unsorted sediment deposited by glaciers- contains a mixture of clay,
silt, sand, gravel and boulders. |
|
Sgpot_Desc |
|
Text, 125 |
e.g., Mostly till
with isolated pockets of sand and gravel. |
A summarized description
of each mapping unit. |
|
Landform |
|
Text, 50 |
See Below |
The geological landform
associated with each mapping unit |
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Alluvial Valley |
Valley carved by
flowing water like a river, stream or creek valley. |
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Beach |
A feature that forms
along a shoreline that usually consists of sorted sands, gravels, and cobbles |
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Collapsed Outwash
Channel |
An outwash channel is a
stream carrying glacial meltwater that deposited sorted silts, sands, gravels,
and cobbles. Collapse is a tern used
to describe an uneven topography where the original sediment was deposited on
top of ice or over buried ice. After
deposition, the ice melted to form an uneven topographic expression. |
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End Moraine |
A glacial landform that
forms at the very end, or terminus, of a glacier. The resulting landform is a ridge-like accumulation of till
that can range from a distinct ridge to a large-scaled hummocky landform. |
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Esker |
A long, narrow,
sinuous, steep-sided ridge composed of irregularly stratified sand and
gravel. The sediments are ice contact
features, meaning that the stream was flowing between ice walls or in an ice
tunnel. |
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Ground Moraine |
Till covered areas with
irregular topography forming gently rolling hills or plains. It is accumulated under glacial ice as
transports and deposits sediment. |
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Ice Contact Feature |
A landform consisting of
sediments that was initially contained or bound by glacial ice. Steep slopes characterize these landforms
where ice once existed. |
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Lake Plain |
Characterized by a flat
topography consisting of sands, silts, and clays formed by the impoundment of
glacial meltwater forming a glacial lake. |
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Lateral Moraine |
A glacial landform that
forms at the side of glacial ice resulting in a ridge-like accumulation of till. |
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|
NA |
Not
applicable/available |
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Outwash Channel |
Stratified sediments,
chiefly sand and gravel, removed or “washed out” from a glacier by meltwater
streams and deposited in a channel or valley. |
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Outwash Feature |
A landform consisting of stratified sediments,
chiefly sand and gravel, removed or “washed out” from a glacier by meltwater
streams and deposited in front of or beyond the
end moraine or the margin of an active glacier. |
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Recessional Moraine |
Consisting of mostly
till as well as stratified sediments.
A recessional moraine forms during brief standstills in a glaciers
retreat. |
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Stagnation Moraine |
Stagnant moraines are formed
by glacial ice that is no longer flowing, but instead, is melting and
depositing sediment that includes flow tills, meltout tills, and stratified
sands and gravels. |
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Thrust Depression |
A low spot in the
topography resulting from glacial ice removing or thrusting the frozen
sediment -usually paired with a corresponding thrusted hill. |
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Thrust Hill |
A hill created by the
thrusting of frozen sediment- paired with a corresponding depression. |
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Thrusted/End Moraine |
This term is used to
describe the Mille Lacs end moraine.
Most of the topography of the moraine is due to thrusting of older
sediment and capped by a variable thickness of Superior Lobe till. |
|
Potential |
|
Text, 50 |
See Below |
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Potential for Sand and
Gravel Resources |
Geologic
units that are inferred to contain sand and gravel. These units exhibit the geologic characteristics that typically
produce sand and gravel deposits.
Existing gravel pit and MN/DOT aggregate sources lying within these
units are considered identified or known resources. These resources include the classes High and Moderate potential
for sand and gravel deposits. |
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Limited Potential for
Sand and Gravel Resources |
Units
that generally have little or no potential for significant aggregate
resources. These units exhibit
geologic characteristics that are typically not consistent with significant
aggregate deposits. These units typically contain clay, silt, fine sand, unsorted
sediments (till), or very thin layers of sand and gravel. These units may
include aggregate deposits that are too small to map. |
|
Class |
|
Text, 50 |
See Below |
|
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|
High Potential for Sand
and Gravel Resources |
Glaciofluvial
features, outwash plains, channels, and terraces as well as ice contact
features like eskers, fans and kames (see Viewshed A and B). Deposits consist typically of sand and
gravel. The probability1
that a potential sand and gravel deposit exists within any mapping unit is
moderately high to very high. Thickness of the deposits ranges from 15 to 40+
feet with less than 15 feet of overburden.
These deposits are moderately large to very large in areal extent2
and the textural characteristics³ are moderately good to very good. The quality4 is typically
moderately high to very high relative to other deposits within Mille Lacs
County. |
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Moderate Potential for
Sand and Gravel Resources |
Glaciofluvial
features, outwash plains, channels, and terraces as well as ice contact
features like eskers, fans and kames.
Deposits consist typically of sand and gravel. The probability that a potential sand and
gravel deposit exists within this unit is moderate to very high. Deposit thickness ranges from 10 to 40+
feet with less than 20 feet of overburden.
These deposits are moderate to large in areal extent and the textural
characteristics are moderate to very good.
The quality is typically moderate to high. |
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Low Potential for Sand and
Gravel Resources |
Glaciofluvial
features, outwash plains, channels, and terraces; ice contact features like
eskers, fans and kames; and alluvial channels. Deposits consist of sand, sand with gravel, or silty sand and
gravel. The probability that a potential
deposit exists within this unit is low to moderately low. Thickness of the deposits ranges from 5 to
40+ feet with overburden thickness ranging from 0 to 50+ feet. These deposits are small to moderate in
areal extent and the textural characteristics are moderately poor to
good. The quality ranges from low to
high. |
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Limited Potential for
Sand and Gravel Resources |
Units
that include glacial features such as scoured glaciofluvial channels, ground moraines,
end moraines, and small alluvial features such as flood plains and
streams. The deposits of this unit
contain all or one of the following: clay with boulders, silt, sand, and/or
gravel. The probability that a
significant sand and gravel deposit exists within this unit is very low to
moderately low. The thickness of
these deposits is typically less than 10 feet but can range from 0 to 30+
feet with overburden thickness ranging from 0 to100 feet. The sand and gravel deposits occurring in
this unit are very small to moderately small in areal extent. The textural
characteristics are poor to moderately good with the quality ranging from
very low to moderately low. |
|
Probablty |
|
Text, 20 |
Very High, High, Moderately
High, Moderate, Moderately Low, Low, Very Low |
The relative degree of
certainty that sand and gravel exists within a unit. Based on air photo
interpretations, field observations, CWI, drilling, presence of gravel pits
and quarries, etc. Each unit is relative to the other units and range
from very high to very low. |
|
Size |
|
Text, 20 |
Very large, Large,
Moderately Large, Moderate, Moderately Small, Small, Very Small |
The relative size of
the sand and gravel deposit |
|
Acreage |
|
Text, 8 |
See Below |
The size of the deposit
in acres. |
|
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|
50+ |
Very Large |
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30-50 |
Large |
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10-30 |
Moderate |
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5-10 |
Small |
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|
<5 |
Very Small |
|
Texture |
|
Text, 20 |
Very Good, Good, Moderately
Good, Moderately Good, Moderate, Moderately Poor, Moderately Poor, Poor. |
A relative scale of the
textural quality of the sand and gravel resource (sieve analysis). The
coarser the material the higher the rating. Fine sand material would
have a poorer rating. See MN/DOT Pit sheets for more detail. |
|
Quality |
|
Text, 20 |
Very High, High,
Moderately High, Moderately High, Moderate, Moderately Low, Low, Very Low |
A relative scale of the
quality of the sand and gravel (soundness, durability, and mineral
makeup). Determined from MN/DOT pit sheets. |
|
Dom_litho |
|
Text, 30 |
See Below |
Glacial Lobe Source |
|
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|
Des Moines Lobe
Sediments |
A glacial lobe that flowed
from the northwest, down the Minnesota River valley to a glacial maximum in
Des Moines, Iowa. A sublobe flowed
north from Mankato into the Twin Cities basin. It is this sublobe that deposited sediment in the southern
portion of Mille Lacs County. A tan,
silty loam with the indicator lithologies of shale and limestones
characterizes the till. Sediment from
this lobe tends to produce aggregate with lower quality due to the water
absorption of the shale and higher percentages of soft limestones and iron
oxides. |
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Des Moines/Superior
Lobe Sediments |
Des Moines Lobe
sediment (see description above) stratigraphically above Superior Lobe sediment (see description
below) |
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Rainy Lobe Sediments |
Rainy Lobe is a northeastern
sourced glacier flowing along the highlands of eastern Minnesota to the
southwest. Rainy Lobe sediments tend
to contain high percentage of granites and granitic rock types. Aggregate with Rainy Lobe rock lithologies
generally are of high quality and durability. |
|
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Superior Lobe Sediments |
Superior Lobe is a
northeastern sourced glacier flowing from the Lake Superior basin to the
southwest. Superior Lobe sediments tend
to contain rhyolites, basalts, and other Duluth Complex rock types. Aggregate with Superior Lobe rock
lithologies generally are of high quality and durability. |
|
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Superior/Rainy Lobe
Sediments |
Superior Lobe sediments
stratigraphically above Rainy Lobe sediments. |
|
Thickness |
|
Text, 15 |
5-15,
10-30, 20-100+ |
Gives range of minimum
and maximum thickness for sand and gravel deposit |
|
Thick_mod |
|
Text, 1 |
+ |
The thickness modifier indicates
that the thickness of the unit exceeds the value listed in the Thick_max
field. |
|
Thick_min |
|
Integer, 4 |
0, 5, 10, 15, 20, 25,
30 |
Describes the minimum
thickness of the sand and gravel unit. |
|
Thick_max |
|
Integer, 4 |
5, 10, 15, 20, 25, 30,
40, 50, 75 |
Describes the maximum
thickness of the sand and gravel unit. |
|
Overburden |
|
Text, 15 |
0-100+,
0-5, 10-50 |
Gives range of minimum
and maximum thickness for overburden |
|
Ob_mod |
|
Text, 1 |
+ |
The overburden modifier
indicates that the thickness of the overburden exceeds the values listed in
the Ob_max field. |
|
Ob_min |
|
Integer, 4 |
0, 3, 10, 20 |
Describes the minimum
thickness of the overburden covering the sand and gravel. |
|
Ob_max |
|
Integer, 4 |
1, 3, 5, 10, 15, 20,
30, 40, 50 |
Describes the maximum
thickness of the overburden covering the sand and gravel. |
|
Buried_dep |
|
Text, 3 |
Yes
or No |
‘Yes’ indicates that the
deposit/mapping unit is buried by significant overburden (30-40 ft.) |
|
Mndot_data |
|
Text, 3 |
Yes or No |
‘Yes’ indicates that
the deposit/mapping unit has a MN DOT ASIS data sourced point (see
millpits.shp, field – SOURCE, value - ‘ASIS’). |
|
Map_label |
|
Text, 2 |
See
Below |
A cartographic map
label for the sand and gravel potential classifications |
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Hp |
High Potential for Sand
and Gravel Resources |
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Mp |
Moderate Potential for
Sand and Gravel Resources |
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Lp |
Low Potential for Sand
and Gravel Resources |
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Lt |
Limited Potential for
Sand and Gravel Resources |