Table Name

Field Name

Begin Column

Definition

Valid Values

Descriptions

Lesuagppy.dbf

Field_unit

 

Integer,4

Values from 100 to 700.

Unique identifier for the field mapping units

 

 

Fieldudesc

 

Text, 60

e.g.,  Colluvium - Slope Wash/Debris; Glaciofluvial Outwash Terrace - 50+ ft Sand w/ Gravel (Low); Holocene Alluvium - Sand (>5 feet); Ice Contact - Sand and Gravel - Low Potential; Sandstone - Quartz Sandstone - White; Till - Slope of Valley Wall.

A short, summarized description of  the field mapping units.

 

 

Sgeo_plb

 

Text, 80

Listed below as Sgeo_plb (Sgeo_lab), youngest units to oldest units.

The surficial geologic unit shown on map Plate B.  Mapping units may be bedrock material, a glacial sediment, or a modern Holocene sediment.

 

 

 

 

Colluvial Sediments (Qcl)

Clay, silt, sand, and gravel, with occasional cobbles and boulders of varying composition, as well as angular fragments of limestone and sandstone of varying sizes.  The sediment is moderately- to poorly-sorted, however, it occasionally contains thin (<6 inch) beds of well-sorted alluvial material.  Colluvium is deposited at the foot of steep slopes where the bank material has collapsed and become slightly washed by sheetwash and alluvial processes.  This colluvial sediment is primarily located at the base of the steep till and bedrock walls paralleling the Minnesota River.

 

 

 

 

Alluvial Flood Plain Sediments (Qfp)

Silt, fine sand, coarse sand, gravel, and clay layers, overlying coarser sand and gravel layers and lenses.  The sediment is generally moderately- to well-sorted and is interpreted to be alluvial overbank and stream bottom deposits.  Within this unit, coarser sediment is typically found in abandoned and modern channels, point bars, and river bars.  Alluvial sediments exist throughout the county in valleys, in low lying areas where drainage occurs as channelized flow, and within the current flood plain of the Minnesota River.

 

 

 

 

Alluvial Fan Sediments (Qaf)

Stratified fine sand, coarse sand, and gravel, with thin layers of silt and clay.  The sediment is moderately well- to very well-sorted.  Coarser material is typically found at the base of the fan (that is, the bottom of the deposit) and near the mouth of the fan.  The sediment is generally deposited at the end of tributary streams where they enter larger valleys, due to the change in slope and slowing of the water flow, forming a cone shaped deposit.  Alluvial fan sediments primarily occur in the western part of the county where smaller tributary streams enter the Minnesota River valley.

 

 

 

 

Alluvial Terrace Sediments (Qat)

Fine sand, coarse sand, and gravel, with occasional layers of silt and clay.  The sediment is moderately well- to well-sorted with thin layers, lenses, and pockets of very well-sorted sands and gravels.  The terraces are typically covered by 6 inches to 2 feet of silt, clay, and/or fine sand layers derived from flood plain sediments.  Alluvial terrace sediments are found along tributary streams that enter the Minnesota River, where moving water has cut through the pre-existing till and glaciofluvial material and redeposited the sorted sands and gravels.

 

 

 

 

Glaciofluvial Outwash Terrace Sediments (Qot)

Stratified sand and gravel with occasional cobbles and small boulders scattered throughout.  The sediment is generally rounded to well-rounded and well- to very-well sorted.  The sediment is interpreted to have been deposited in large distal meltwater channels, such as the ones paralleling the Minnesota River near Kasota and LeSueur.  Glacial River Warren, which drained Glacial Lake Agassiz, was responsible for the deposition of these large terraces.

 

 

 

 

Glaciofluvial Outwash Channel Sediments (Qoc)

Stratified fine to coarse sand and gravel, with occasional layers of silt, fine sand, and cobbles scattered throughout.  The sediment is generally rounded to well-rounded and well- to very-well sorted.  The sediment is interpreted to be derived from large meltwater channels that ran on, within, and/or beneath the retreating glacier and from the drainage channels of large glacial lakes.  Much of the sediment is collapsed and discontinuous, which resulted from the melting and collapse of the sediments overlying glacial ice or buried ice blocks.  However, large continuous sand and gravel outwash channel sediments are found near Waterville.

 

 

 

 

Outwash Channel Sediments Modifying Till Sediments (Qto)

Discontinuous, patchy, and thin stratified fine to coarse sand and gravel, with occasional layers of silt, fine sand, and cobbles, typically overlying unsorted till sediments (unsorted clay, silt, sand, gravel, cobbles, and boulders).  The outwash sediment is interpreted to have been derived from smaller meltwater channels that ran on, within, and/or underneath the retreating glacier and from the drainage channels of glacial lakes.  These outwash modified till sediments are primarily located in the southeast part of the county.

 

 

 

 

Glaciolacustrine Sediments over Till Sediments (Qgl)

Alternating silt and clay layers with layers of silt, clay, fine-sand, and medium sand overlying unsorted till sediments (unsorted clay, silt, sand, gravel, cobbles, and boulders).  These sediments are typically deposited as thin layers with distinctive summer and winter banding called varves.  The sediment is interpreted to be derived from suspended material brought by meltwater streams, running on top of melting glaciers, into ice walled glacial lakes.  These glaciolacustrine sediments are scattered throughout the county and vary in size from a few acres to nearly 9,000 acres, and vary in thickness from less than a few feet to roughly 10 feet.

 

 

 

 

Ice Contact Sediments (Qic)

Stratified silt, fine sand, coarse sand, and gravel, with occasional clay and silt layers.  The sediment is generally rounded to well-rounded and poorly- to well-sorted.  These sediments are deposited as features called eskers and kames.  These eskers are typically long, narrow, sinuous ridges of stratified sand and gravel that were formed as sub-glacial streams flowed between ice walls or in ice tunnels within the stagnant glacier, and were left behind as the ice melted.  The kame features are low mounds, knobs, hummocks, or short irregular ridges also composed primarily of stratified sand and gravel that were formed in low areas or holes on the surface of the ice as fans or deltas.  The smaller ice contact sediments were not sorted as well and still contain a significant amount of silt and clay within the sand and gravel.  These sediments can be found throughout the county, however, well developed eskers can be observed in the southeastern part of the county.

 

 

 

 

Till - Collapsed Channel Sediments (Qcc)

Till sediment (unsorted clay, silt, sand, gravel, cobbles, and boulders), with occasional, discontinuous and patchy, fine to coarse sand and gravel sediment.  The sand and gravel sediment, overlying the till, is all that remains of small outwash channels where supra-glacial meltwater once carried large amounts of sand, gravel, and fine sediments.  The sediment has been cleaned out of the channels and is often deposited as outwash channels further down gradient.  These collapsed channel sediments can be observed in the southern and southeastern portions of the county.

 

 

 

 

Till - Ground Moraine Sediments - Low Relief (Qtl)

Unsorted and unstratified clay, silt, sand, and gravel, with scattered cobbles and  boulders throughout.  This till sediment (also called unsorted drift) was deposited directly by and underneath the glacier without subsequent reworking by meltwater.  The random melting of ice and deposition of material produced a relatively flat to gently rolling, slightly hummocky topography that is characteristic of a ground moraine.

 

 

 

 

Till – Stagnant Ice Moraine Sediments - Moderate Relief (Qtm)

Unsorted and unstratified clay, silt, sand, and gravel, with scattered cobbles and  boulders throughout.  This till sediment was deposited directly by and underneath the glacier without subsequent reworking by meltwater.  The random melting of ice and deposition of material produced a hummocky, undulating, or hilly topography.  The topography is also characterized by circular flat-topped hills, or plateaus, which are mostly till, but may be capped with glaciolacustrine sediments.

 

 

 

 

Till – Stagnant Ice Moraine Sediments - Higher Relief (Qth)

Unsorted and unstratified clay, silt, sand, and gravel, with scattered cobbles and boulders throughout.  This till sediment was deposited directly by and underneath the glacier without subsequent reworking by meltwater.  The random melting of ice and deposition of material produced a very hummocky, undulating, or hilly topography characteristic of a stagnant ice moraine.  The topography is also characterized by circular flat-topped hills, or plateaus, which are mostly till, but are capped with glaciolacustrine sediments.  There are several collapsed channels located throughout this unit.

 

 

 

 

Till, Sand, and Gravel Complex Sediments (Qts)

Till (unsorted clay, silt, sand, gravel, cobbles, and boulders) overlying and mixed with relatively small, patchy, discontinuous, and thinly stratified, fine to coarse sand and gravel, with occasional layers of clay, silt, and fine sand.  The area consists of small ice contact and outwash deposits within a stagnant ice moraine.  This area is interpreted to have been dominated by meltwater drainage, however, a later glacial event covered the outwash with till creating a complex of sand and gravel and till.  The random melting of ice and deposition of material produced a very hummocky, undulating, or hilly topography characteristic of a stagnant ice moraine.  This complex of sediments can be observed in the southeastern corner of the county.

 

 

 

 

Glaciofluvial Outwash (Superior Lobe) Sediments (Qos)

Stratified sand and gravel, with occasional layers of cobbles, fine sand, and silt scattered throughout.  The sediment is generally rounded to well-rounded and moderately well- to very well-sorted.  The sediment is interpreted to be derived from the meltwater drainage of the Superior Lobe (a much earlier glacial advance that transported and deposited sediment from the northeast).  This sediment is generally coarser than any other outwash sediment in the county.  The sand and gravel sediment is primarily composed of igneous rocks from the Lake Superior region, such as gabbros and basalts, whereas every other sand and gravel deposit within the county consists primarily of carbonates, granites, shales, and other rocks from sources to the northwest.  This sediment can only be observed in the extreme northwestern portion of the county, where this buried layer was exposed by the down-cutting of Glacial River Warren.

 

 

 

 

Limestone/Dolomite (Ols)

Light brown, brownish gray to buff, fine- to medium-grained dolomitic limestone with a silt-sized dolomite matrix.  Thin to thick bedded with variable color and texture both horizontally and vertically.  Some of the lower beds are thicker and very well consolidated.  This unit is frequently porous and cavernous, with the caverns commonly lined with calcite crystals.  Chert nodules and fossils are common throughout.  This unit may contain small pockets of weathered carbonate material near the surface.

 

 

 

 

Sandstone (Css)

White, yellowish to light-brownish tan, and buff colored, medium to thick bedded, poorly cemented, coarse- to medium-grained quartzose sandstone to dolomitic sandstone.  The upper unit contains alternating layers of quartzose sandstone, dolomitic limestone, and dolomitic sandstone and grades downward to fairly pure quartzose sandstone, then into well-consolidated sandstone, and finally into loosely consolidated sandstone.  The quartz purity of this unit increases downward until it is > 95% pure quartz sandstone.  This unit is currently being mined for industrial quality sand within LeSueur County.

 

 

Sgeo_lab

 

Text, 4

Qaf, Qfp, Qat, Qcl, Qos, Qoc, Qot, Qgl, Qic, Ols, Qto, Css, Qcc, Qtl, Qth, Qtm, Qts

The label for the surficial geology mapping unit used on map Plate B.

 

Sgeo_age

 

Text,30

Cambrian, Holocene, Holocene/Ordovician, Holocene/Pleistocene, Ordovician, Pleistocene, Pleistocene/Ordovician

Describes the age of the material encountered at the surface.

 

Sgeo_proc

 

Text, 40

 

The type of geological process that deposited these features.

 

 

 

 

Alluvial

Modern stream processes

 

 

 

 

Alluvial over Glaciofluvial

Modern stream processes overlying glaciofluvial (glacial stream) processes

 

 

 

 

 

Bedrock

Material deposited by ancient seas during the Cambrian and Ordovician.

 

 

 

 

Colluvial

Material that was deposited as slope wash or slump along steep banks.

 

 

 

 

Glacial

Unsorted glacial material deposited in place.

 

 

 

 

Glacial over Glaciofluvial

Unsorted glacial material deposited over glacial sediments that have been sorted by meltwater.

 

 

 

 

Glaciofluvial

Glacial sediments that have been sorted by meltwater.

 

 

 

 

Glaciolacustrine

Sediments deposited at the bottom of a glacial lake.

 

Sgeo_feat

 

Text, 50

Alluvial fan, Alluvial terrace, Bedrock, Collapsed channel, Colluvial slope, Flood plain, Glacial lake bed, Ground moraine, Ice contact, Outwash channel, Outwash terrace, Sand bar, Stagnant ice moraine.

The type of geological feature encountered at the surface (surficial geology).  Surficial Geology is defined as the geologic units encountered within the top 5 to 10 feet of the surface.

 

Sgeo_mat

 

Text, 40

e.g., Clay, silt, and sand over till; Sand; Sand and gravel; Limestone; Till with patchy sand and gravel.

The dominant type of material encountered in the surficial geologic unit.

 

Sg_sigpot

 

Text, 50

Potential Sand and Gravel Resources; Potential Crushed Stone Resource; Limited Potential for Aggregate Resources.

Significant Aggregate Resources Deposits are defined as those deposits most likely to be explored and evaluated for future commercial use.  They include all the moderately and highly desirable sand, gravel, and crushed stone deposits as well as very large areas of finer sand and gravel that could be blended with coarser material to make more highly desirable deposits.

 

Sg_potpla

 

Text,100

e.g., Highly Desirable Sand and Gravel Deposits; Less Desirable Sand and Gravel Deposits/Moderately Desirable Crushed Stone Deposits; Limited Potential Aggregate Resources.

The aggregate resource potential, combined from the Sg_pota_sg and Sg_pota_cs fields.

 

Sg_pota_sg

 

Text,50

 

The aggregate resource potential for sand and gravel, as shown on map Plate A.  From the legend on Plate A….

POTENTIAL 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 indicate identified or known resources.  The geologic units having potential for sand and gravel include alluvial features (flood plains, terraces, and fans), glacial outwash features (channels and terraces), and ice-contact features (eskers and kames).  These units typically contain sorted sand and gravel with little silt or clay.

 

 

 

 

Highly Desirable Sand and Gravel Deposits

Glaciofluvial features, such as terraces and outwash channels. These deposits are very large in areal extent.  These deposits consist of sand and gravel with thicknesses typically ranging from 15 to 75+ feet, with less than 5 feet of overburden.  The probability that a potential sand and gravel deposit exists within this unit is high to very high.  The textural characteristics of these deposits are classified as good to very good.  The quality is typically moderately high to very high relative to all deposits within LeSueur County.

 

 

 

 

Moderately Desirable Sand and Gravel Deposits

Glaciofluvial features, such as outwash channels and terraces; ice-contact features, such as eskers and kames; as well as Holocene age terraces, floodplains, and fans.  These deposits are moderately small to large in areal extent with sand and gravel thicknesses typically ranging from 10 to 50+ feet, with less than 10 feet of overburden.  The probability that a potential sand and gravel deposit exists within this unit is moderately high to very high.  The textural characteristics of these deposits are moderate to very good, with the quality ranging from moderately high to high.

 

 

 

 

Less Desirable Sand and Gravel Deposits

Glaciofluvial features, such as outwash channels and terraces; ice-contact features, such as eskers and kames; and alluvial features such as flood plains, terraces, fans, and sand bars.  These deposits are moderately small to very large in areal extent and consist of sand and fine sand with thicknesses ranging from 0 to 50+ feet, with overburden thicknesses between 0 to 40+ feet.  The probability that a potential sand and gravel deposit exists within this unit is moderate to very high.  The textural characteristics of these deposits are moderately poor to good, with the quality ranging from moderately low to high.

 

 

 

 

Limited Potential Sand and Gravel Deposits

or

Limited Potential for Aggregate Deposits

Units that include glacial features such as collapsed glaciofluvial channels, ground moraines, glacial lake beds, colluvial slopes, and small alluvial features such as flood plains and streams.  The probability that a significant aggregate deposit exists within this unit is very low to moderate.  The aggregate deposits occurring in this unit are very small to moderately small in areal extent and typically consist of finer material (sand with some gravel).  The thicknesses of these aggregate deposits are typically less than 20 feet, with overburden thicknesses sometimes reaching over 100 feet.  The textural characteristics are poor to moderately poor with the quality ranging from low to moderate.  These units also contain carbonate bedrock units with an overburden thickness of greater than 50 feet.  In a few areas on the map, a dotted pattern (indicating crushed stone resources potential) can be seen, lying over this mapping unit.  In this case, there is crushed stone potential, but there is limited sand and gravel potential.

 

Sg_pota_cs

 

Text,50

 

The aggregate resource potential for crushed stone, as shown on map Plate A.  From the legend on Plate A…

POTENTIAL CRUSHED STONE RESOURCES:  Carbonate (limestones and dolomites) bedrock from the Prairie du Chien Group and sandstone bedrock from the Jordan Sandstone Formation that are suitable for crushing.  These units are inferred to be relatively thick (10 to 50+ feet), with overburden thicknesses ranging from 0 to 50 feet.  Quarries located within these units indicate identified or known resources.

 

 

 

 

Highly Desirable Crushed Stone Deposits

Carbonate (limestones and dolomites) bedrock units that are very large in areal extent, and contain materials suitable for crushing.  These units have thicknesses ranging from 30 to 50+ feet, with overburden thicknesses typically less than 10 feet.  These units have a very high probability of containing potential crushed stone deposits.  The quality of these units is high.

 

 

 

 

Moderately Desirable Crushed Stone Deposits

Carbonate (limestones and dolomites) bedrock units that are moderate to very large in areal extent, and contain materials suitable for crushing.  These units have thicknesses ranging from 20 to 40+ feet, with overburden thicknesses typically less than 10 feet.  These units have a high to very high probability of containing potential crushed stone deposits.  The quality of these units is high.

 

 

 

 

Less Desirable Crushed Stone Deposits

Carbonate (limestones and dolomites) and sandstone bedrock units that are moderately large to very large in areal extent, and contain materials suitable for crushing.  These units have thicknesses ranging from 10 to 50+ feet, with overburden thicknesses ranging from 0 to 50 feet.  These units have a moderately high to very high probability of containing potential crushed stone deposits.  The quality of these units is moderately high to very high.

 

Sg_prob

 

Text, 20

Very High, High, Moderately High, Moderate, Moderately Low, 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.

 

Sg_depsize

 

Text, 20

Very large, Large, Moderately large, Moderate, Moderately small, Small

The relative size of the sand and gravel deposit

 

Size_in_ac

 

Text, 7

>50, 40-50, 30-40, 20-30, 10-20, 5-10

The size of the deposit in acres.

 

Sg_thickmn

 

Integer, 4

0, 5, 10, 15, 20, 25, 30

Describes the minimum thickness of the sand and gravel unit.

 

Sg_thickmx

 

Integer, 4

5, 10, 15, 20, 25, 30, 40, 50, 75

Describes the maximum thickness of the sand and gravel unit.

 

Sg_thickmd

 

Text,1

+

The sg_thickness modifier indicates that the thickness of the unit exceeds the value listed in the Sg_thickmx field.

 

Sg_overmin

 

Integer,4

0, 3, 10, 20

Describes the minimum thickness of the overburden covering the sand and gravel.

 

Sg_overmax

 

Integer,4

1, 3, 5, 10, 15, 20, 30, 40, 50

Describes the maximum thickness of the overburden covering the sand and gravel.

 

Sg_overmod

 

Text,1

+

The sg_overburden modifier indicates that the thickness of the overburden exceeds the values listed in the Sg_overmax field.

 

Sg_texture

 

Text, 20

Very Good, Good, Moderately Good, Moderate/Good, Moderate, Moderately Poor, Poor/Good, 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.

 

Sg_quality

 

Text, 20

Very High, High, Moderately High, Moderate/High, Moderate, Moderately Low, Low/High, Low

A relative scale of the quality of the sand and gravel (soundness, durability, and mineral makeup).  Determined from MN/DOT pit sheets. 

 

Sg_thick

 

Text, 15

e.g., 0-5, 5-30+, 20-40, 25-75+

The assumed range of thickness of the sand and gravel deposit (in feet).  A combination of the Sg_thickmn, Sg_thickmx, and Sg_thickmd fields.

 

Sg_overbdn

 

Text, 15

e.g.,  0-1, 0-20+, 10-20, 20-40+

 

The assumed range of overburden thickness of a sand and gravel deposit (in feet).  A combination of the Sg_overmin, Sg_overmax, and Sg_overmod fields.