Table Name |
Field Name |
Begin Column |
Definition |
Valid Values |
Descriptions |
millmgsbg.shp |
Geol_Srce |
|
Text, 150 |
See Below |
The bedrock geology mapping units source. |
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|
MGS Miscellaneous Map
Series M-100: Bedrock Geology of
Mille Lacs County 30 X 60 Minute Quadrangle, 1:100,000, 1999 |
Minnesota Geological Survey
(MGS) sourced mapping units at a scale of 1:100,000 covering the northern
half of Mille Lacs County |
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|
|
|
MGS Miscellaneous Map
Series M-132: Bedrock Geology and
Superimposed Magnetic on Gravity Anomaly for East-Central Minnesota,
1:200,000, 2003 |
MGS sourced mapping units
at a scale of 1:200,000 covering most of the southern half of Mille Lacs
County. |
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|
|
Interpreted by the MN DNR,
1:200,000, 2006 |
Mapping unites interpreted
by the Minnesota Dept. of Natural Resources (MN DNR) at a scale of 1:200,000. The units cover the far southeast corner of Mille Lacs County
for purpose of having a complete bedrock geology dataset of Mille Lacs
County. |
|
GEOC_DATE |
|
Number, ,0 |
Ex: 19990423 |
Date that the mapping units
were delineated |
|
MGS_DESC |
|
Text, 75 |
Ex: Bedrock Near Surface, Bradbury Creek Granodiorite, Cambrian Undifferentiated, Denham Fm, Hillman Migmatite, Mafic-Ultramafic Intrusions, Mille Lacs Group |
MGS description of bedrock geology mapping units (21) extracted from source map datasets. For more information about this datasets visit http://www.geo.umn.edu/mgs/ and search for miscellaneous map series’ M-100 & M-132. |
|
MGS_DESC |
|
Text, 75 |
See Below |
MN DNR’s generalization/reclassification of MGS bedrock geology mapping units (MGS_DESC) into 8 mapping units for purpose of mapping crushed stone potential of Mille Lacs County |
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Gneiss |
Durable medium to coarse-grained, crystalline,
metamorphic rock. This bedrock is pinkish-gray
that is variably sheared and foliated.
However, the quality is broadly interpreted as high for crushed stone
resources. Quality and durability are
affected by the local extent and degree of metamorphism, which is observed by
the orientation of larger mineral grains, shearing, foliation, and mineral
elongation. Specific gravity typically ranges from 2.5 to 2.9. This unit combines MGS bedrock map units
Apg, Amc, and Amcu. |
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Granitic Rocks |
Durable
coarse-grained, crystalline rock.
This bedrock unit combines several granitic, tonalitic, and
granodioritic rock formations, which vary in color, composition, and physical
properties. The quality is
interpreted as high for crushed stone resources. Local occurrences of preferred orientation of larger minerals,
large crystal size, shearing, foliation, and elongation of minerals may lower
the quality and durability of this unit in some areas. Specific gravity
typically ranges from 2.5 to 2.7.
This unit combines MGS bedrock map units Pbm, Pfm, Pgr, Phm, Phmu,
Piw, Piwu, and Pwi. |
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|
Mafic and Ultramafic
Intrusion |
Contains
a variety of minerals and rock types, typically serpentinized peridotite, pyroxenite,
hornblendite, diorite, and gabbro with some granodiorite. This quality of this rock is variable
depending on dominant lithology; however, quality is broadly interpreted be
moderate. Quality and durability
improve with larger intrusions, distance from contacts of other rock units,
and degree of fracturing within rock.
Specific gravity typically ranges from 2.6 to 3.0. This unit combines MGS bedrock map units
Pmi, Pp, and Ppu. |
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Metamorphosed Sedimentary
Rock |
Predominantly
schist and interpreted to have limited crushed stone potential. Variability
of composition and degree of metamorphism all contribute to non-durability
and low quality of these rocks. This
unit combines MGS bedrock map units Pps and Ppsu. |
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|
Schist |
Predominantly consists of schist derived from volcanic
and sedimentary rocks and is unsound and non-durable rock that is
characterized by a high degree of metamorphism. The minerals in schist tend be elongated and easily fractured
into flakes and slabs, which contribute to non-durability and low
quality. This unit combines MGS
bedrock map units Pdam, Psm, and Psv. |
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Sedimentary Rocks |
Poorly lithified sedimentary rocks, which include sandstone,
siltstone, and shale. These rocks are friable, commonly contain high clay
content, and cleave along bedding planes, which contribute to non-durability
and low quality. This unit consists of MGS bedrock map unit C. |
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Shear Zone |
Highly fractured and deformed granitic rock, cut by
numerous northeast-trending mafic dikes. The aggregate potential of this unit
is limited due to the extent of alteration and shearing. This unit consists of MGS bedrock map unit
Psz. |
|
MGS_MAPLBL |
|
Text, 5 |
Ex: C, Psv, Pp, Pbm, Pfm |
A map label related to MGS bedrock geology mapping units (MGS_Desc) |