# Redwood County, Minnesota - Sand and Gravel Potential

This page last updated: 10/02/2022
Metadata created using Minnesota Geographic Metadata Guidelines

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1. Overview
2. Data Quality
3. Data Organization
4. Coordinate System
5. Attributes
6. Distribution - Get Data
7. Metadata Reference

## Section 1: Overview

Originator: Minnesota Department of Natural Resources, Division of Lands and Minerals, Mineral Potential Evaluation Section
Title: Redwood County, Minnesota - Sand and Gravel Potential
Abstract: This dataset consists of information about the geology, geological characteristics, and sand and gravel potential of 918 map units. Five fields relate to the surficial geology of the map unit, including a unique map unit id, sediment, landform, surficial geology description, and dominant lithology. Six fields relate to sand and gravel characteristics, including probability, quality, texture, overburden thickness, deposit size, and sand and gravel thickness. These characteristics were used to calculate the aggregate potential of the map unit for sand and gravel.
Purpose: To summarize the geological characteristics, surficial geology, and aggregate potential (sand, gravel) of the different units. To help categorize the geological characteristics and incorporate them into a model to help determine the aggregate potential of the deposit.
Time Period of Content Date: 2022
Currentness Reference: Data were gathered in the summer and fall of 2021. Data were compiled and interpreted during the spring and summer of 2022.
Progress: Complete
Maintenance and Update Frequency: None Planned
Spatial Extent of Data: Redwood County, Minnesota
Bounding Coordinates: -94.86
-95.62
44.71
44.19
Place Keywords: Redwood County, Minnesota
Theme Keywords:
Theme Keyword Thesaurus: Aggregate potential, sand and gravel, surficial geology, geomorphology, glacial geology, geological characteristics, probability, quality
Access Constraints:
Use Constraints: Acknowledgement of the Minnesota Department of Natural Resources is appreciated for products derived from these data.
Contact Person Information: ,
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Phone:
Email:
Browse Graphic: None available
Associated Data Sets:

## Section 2: Data Quality

Attribute Accuracy:
Logical Consistency:
Completeness: The sand and gravel potential map units were delineated using ArcGIS 10.6. Delineations are based on the interpretation of high resolution elevation data (LiDAR) using 3 meter cell-sized digital elevation model; several sets of DOQ’s with flight dates ranging from the 1938 to 2019 and at varying scales; and fieldwork including visits to several gravel pits. Digitizing was completed at a scale of 1:24,000. The final data sets represent a reconnaissance-scale survey mapped at 1:50,000.
Horizontal Positional Accuracy:
Lineage: Color, color-infrared (CIR), and black-and-white aerial photographs were used to delineate geological landforms and aggregate resources. Sources include; Stereoscopic pairs of color infrared aerial photographs (NAPP, 9in x 9in at 1:40000 scale, April 1991 and April 1992); On-screen landform analysis was used with FSA (Farm Services Administration) Color Aerial Photography collected from the following years, with their associated pixel resolution in parenthesis; 2003-04 (1 meter), 2005 (10 meter), 2006 (10 meter), 2008 (1 meter), 2009 (1 meter), FSA CIR (Color Infrared) Imagery collected in 2008 (1 meter), FSA Imagery collected in 2010 (1 meter); and National Agricultural Imagery Program (NAIP) 2009-2019 imagers (1 meter). Aerial photographic interpretation was completed with a glacial mapping technique known as the land systems approach. This technique relies on the principle that depositional glacial landforms are composed of a predictable range of sediments, some consisting of sorted sand and gravel and others consisting of silts, clays, or unsorted materials. In addition to the land systems approach, several other general characteristics helped determine the nature of the material, such as tonal contrasts, texture, context, shape, size, trend, association, and patterns. These characteristics can help determine the properties of the surface material (e.g., certain vegetation grows on well drained soils such as sand and gravel, which on an aerial photograph has a distinctive texture, tone, pattern, etc.).
The landform recognition approach (part of the land systems approach) was also used when interpreting the topography within the project boundary. Glacial landforms have distinct and unique shapes and patterns that can be observed in their topographic expression. Topographic maps (USGS 1:24000), digital elevation models, and shaded relief maps were all used to help delineate these sand and gravel bearing features. The topographic expression of a feature can also be observed by looking at the distribution of lakes and wetlands. For example, a string of lakes and/or wetlands may be the signature of a glacial outwash channel or collapsed channel, which may host sand or gravel deposits. Several aggregate bearing features were located using this technique (outwash channels, ice contact features, alluvial fans, terraces, etc.).
Other mapping sources include the 3-meter LiDAR DEMs (Digital Elevation Models) from Redwood County; and CWI (County Well Index) database of located and unlocated wells from the Minnesota Department of Health and MGS (Minnesota Geological Survey), downloaded in 2021. Related geological maps were referenced including: MN DNR Report 363 Plate A, and Plate 3 from Setterholm, Dale, R.. (2016). C-36, Geologic Atlas of Redwood County, Minnesota. Minnesota Geological Survey. Retrieved from the University of Minnesota Digital Conservancy, https://hdl.handle.net/11299/182069. Gravel pits and quarries were extracted from several sources (refer to redw_pits) and reviewed in the field or on air photos.

## Section 3: Spatial Data Organization (not used in this metadata)

## Section 4: Coordinate System

Horizontal Coordinate Scheme: Universal Transverse Mercator
UTM Zone Number: 15
Horizontal Datum: NAD83
Horizontal Units: meters
Vertical Datum:
Vertical Units:
Depth Datum:
Depth Units:

## Section 5: Attributes

Overview: The polygons were delineated to represent geological features, geological characteristics, and aggregate potential for sand and gravel.
Detailed Citation:
Table Detail:

pot_redwood
Field Name | Valid Values | Definition | Definition Source
--- | --- | --- | ---
SGPOT_ID | - | Unique identifier for the field- mapping units. | Esri
Sediment | enumerated | General description of the dominant sediment material for each mapping unit. Multiple values may be used in descriptions. |
| Clay | Clay is very fine-grained sediment that is less than 0.004 mm in size. |
| Silt | Rock fragments that have a diameter between 0.004 to 0.0625 mm. |
| Sand | Rock fragments that range in diameter from 0.0625 to 2 mm. |
| Sand minor 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 between 5-15% by volume gravel. |
| 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 between 15-35% by volume gravel. |
| 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 between 35-50% by volume gravel. |
| Gravel | Rock fragments of specific particle size that is larger than 2 mm and less than 63 mm. |
| Boulder | Rocks with a diameter >10 inches. |
| Organics | Soil that contains decaying organic matter. |
| Till | A term used to describe the unsorted sediment deposited by glaciers- contains a mixture of clay, silt, sand, gravel, cobbles and boulders. |
| Cobbles | Rocks with a diameter between 3-10 inches. |
| Organics | Soil that contains decaying organic matter. |
| Fine Sand | Rocks and minerals that range in diameter of 0.0625 to 0.25 mm. |
| Granite | A felsic igneous rock that has medium to coarse crystalline texture. Includes granite, quartz monzonite, and granodiorite based on Minnesota Geological Survey bedrock descriptions. Referred to as “Sacred Heart Granite”. |
| Granite/Gneiss | A coarse-grained crystalline and metamorphic rock. Includes foliated, biotite tonalitic to granodioritic gneiss based on Minnesota Geological Survey bedrock descriptions. Referred to as “Morton Gneiss”. |
| Bedrock | General term to describe consolidated rock underneath the surface. Bedrock outcrop is where bedrock can be seen above the surface. |
SGPOT_DESC | - | A summarized description of each mapping unit. |
Thickness | - | Gives range of minimum and maximum thickness for sand and gravel deposit. |
Thick_mod | - | The thickness modifier indicates that the thickness of the unit could exceed the value listed in the Thick_max field. |
Thick_min | - | Describes the minimum thickness of the sand and gravel unit. |
Thick_max | - | Describes the maximum thickness of the sand and gravel unit. |
Overburden | - | Gives range of minimum and maximum thickness for overburden. |
OB_MOD | - | The overburden modifier indicates that the thickness of the overburden exceeds the values listed in the Ob_max field. |
OB_MIN | - | Describes the minimum thickness of the overburden covering the sand and gravel. |
OB_MAX | - | Describes the maximum thickness of the overburden covering the sand and gravel. |
MAP_LABEL | enumerated | A cartographic map label for the sand and gravel potential classifications. |
| Hp | High Potential for Sand and Gravel Resources |
| Mp | Moderate Potential for Sand and Gravel Resources |
| Lp | Low Potential for Sand and Gravel Resources |
| Ltd | Limited Potential for Sand and Gravel Resources |
Landform | enumerated | The geological landform associated with each mapping unit. |
| Alluvial Valley | Valley carved by flowing water like a river, stream, or creek valley. |
| Collapse Feature | Landform that was deposited in or on glacial ice that subsequently collapsed |
| End Moraine Complex | The terminal, or furthest, position of ice. This map unit includes end moraines that were either deposited by an accumulation of sediment and/or end moraines formed by glacial thrusting of older sediments and bedrock. |
| Glacial Lake | Generally a broad flat or depressed area, formally occupied by a large body of water supplied by melting glacial ice. Characterized by fine sediments deposited in stagnant water. |
| Glacial Lake/Delta | Landforms created as water flowed into a large glacial lake, depositing coarser grained sediments. |
| 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. |
| Alluvial Plain | Flat landform composed of sediments deposited by multiple flood events of a river. |
| Alluvial Terrace | Former river floodplains that were abandoned as the river cut deeper into the landscape. |
| Colluvial Feature | Sediment that accumulated at the base of a steep slope by falling from above. |
| Moraine | This mapping unit includes sequences of till accumulated either at the end (end moraine) and/or the side (lateral moraine) of glacial ice. |
| 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. |
| Stagnation Feature | Features associated with the stagnation of a glacier. |
| Outwash Feature |  |
| Outwash Channel | A landform consisting of stratified sediments, chiefly sand and gravel, removed or “washed out” from a glacier by meltwater, typically deposited in a large broad channel. |
| Tunnel Valley | Valley carved by a subglacial stream. |
| Alluvial Fan | A fan-shaped mass of alluvium deposited as the flow of a stream decreases in velocity, typically from a narrow canyon onto a valley floor. |
| Bedrock Outcrop | Bedrock is a general term to describe consolidated rock underneath the surface. Bedrock outcrop is where the bedrock can be seen above the surface. |
| Colluvium | Composed of unconsolidated sediments deposited at the base of steep slopes |
Potential | enumerated |  |
| Significant Potential for Sand and Gravel Resources | Geologic units that are inferred to contain sand and gravel resource potential. These units exhibit the geologic characteristics associated with sand and gravel-bearing landforms. Existing gravel pit and MNDOT aggregate sources within these units are considered identified or known resources that increase the level of confidence for that mapping unit. These resources include the classes High and Moderate potential for sand and gravel deposits. |
| Nonsignificant Potential for Sand and Gravel Resources | Units that generally have little or no potential for significant aggregate resources or lack sufficient data to support a classification of significant aggregate resources. These units typically contain clay, silt, fine sand, unsorted sediments (till), very thin layers of sand and gravel, or have significant overburden. Nonsignificant potential regions also coincide where bedrock is at or near the surface, or these units may include aggregate deposits that are too small to map. |
Class | enumerated |  |
| High Potential for Sand and Gravel Resources | Includes landforms such as alluvial valleys, outwash channels, outwash features, and outwash terraces. Predominant sediment typically consists of gravel with sand to sand and gravel. The probability2 that a potential sand and gravel resource exists within any map unit is moderately high to very high. Deposit thickness ranges from 0-35+ feet with 0-5+ feet of overburden3. The sand and gravel resources occurring in this unit are moderate to very large in areal extent4 and the textural characteristics5 are moderately good to very good. The quality6 is moderate to high, relative to other sand and gravel resources within Redwood County. |
| Moderate Potential for Sand and Gravel Resources | Includes landforms such alluvial valleys, outwash features, outwash channels, outwash terraces, ice contact features, and ground moraine. Predominant sediment ranges from sand with minor gravel to sand and gravel. The probability that a potential sand and gravel resource exists within any map unit is moderate to high. Deposit thickness is typically 0-25+ feet with 0-10+ feet of overburden. The sand and gravel resources occurring in this unit are small to very large in areal extent and the textural characteristics are moderate to good. The quality is typically moderately low to high relative to other sand and gravel resources within Redwood County. |
| Low Potential for Sand and Gravel Resources | Includes landforms such as alluvial valleys, alluvial fans, colluvium, outwash features, outwash channels, outwash terraces, ice contact features, ground moraine, and modified ground moraine. Predominant sediment varies and can include sandy till, sand, silt, and sand with minor gravel. The probability that a significant sand and gravel resource exists within this unit is low to moderate. The thickness of the deposits is typically 0-15+ feet with overburden thickness ranging from 0-35+ feet. The sand and gravel resources occurring in this unit are very small to very large in areal extent and textural characteristics are poor to moderately good. The quality ranges from low to moderately high relative to other sand and gravel resources within Redwood County. |
| Limited Potential for Sand and Gravel Resources | Includes landforms such alluvial valleys, alluvial fans, outwash features, outwash channels, outwash terraces, ice contact features, moraines, ground moraine, modified ground moraine, and bedrock outcrops. The deposits of this unit contain all or one of the following: clay with boulders (till), clay, silt, sand, and organics. The probability that a significant sand and gravel resource exists within this unit is very low to moderately low. The thickness of the deposits is typically 0-10+ feet with overburden thickness ranging from 0-50+ feet. The sand and gravel resources occurring in this unit are very small to moderately small in areal extent and textural characteristics are very poor to moderately poor. The quality ranges from very low to moderately low relative to other sand and gravel resources within Redwood County. A limited potential rating includes the circumstance where characteristics are unknown; there was insufficient data to give a higher ranking; limited access to an area for further investigation; and/or no obvious landform-sediment association. |
Probability | - | The relative degree of certainty that sand and gravel exists within a unit. Based on air photo interpretations, field observations, CWI, presence of gravel pits, etc. Each unit is relative to the other units and range from very high to low. |
Acreage | enumerated | The approximate size of the deposit in acres. |
| Very Large | 30+ |
| Large | 20-30 |
| Moderately Large | 15-20 |
| Moderately Small | 5-10 |
| Moderate | 10-15 |
| Small | 3-5 |
| Very Small | < 3 |
Texture | - | 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 MNDOT Pit sheets for more detail. |
Quality | - | A relative scale of the quality of the sand and gravel (soundness, durability, and mineral makeup). |
Dom_Litho | enumerated | Glacial Lobe Source |
| 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 tan, silty loam with the indicator lithologies of shale and limestone 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 limestone and iron oxides. |
| Granite | A felsic igneous rock that has medium to coarse crystalline texture. Includes granite, quartz monzonite, and granodiorite based on Minnesota Geological Survey bedrock descriptions. Referred to as “Sacred Heart Granite”. |
| Granite/Gneiss | A coarse-grained crystalline and metamorphic rock. Includes foliated, biotite tonalitic to granodioritic gneiss based on Minnesota Geological Survey bedrock descriptions. Referred to as “Morton Gneiss”. |

## Section 6: Distribution

Publisher: Minnesota Department of Natural Resources (DNR)
Publication Date: 10/04/2022
Contact Person Information: ,
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Phone:
Email:
Distributor's Data Set Identifier: Redwood County Aggregate Resources, Sand and Gravel Potential
Distribution Liability: The State of Minnesota makes no representations or warranties express or implied, with respect to the use of the information contained herein regardless of its format or the means of its transmission. There is no guarantee or representation to the user as to the accuracy, currency, suitability, completeness, usefulness, or reliability of this information for any purpose. The user accepts the information “as is." The State of Minnesota assumes no responsibility for loss or damage incurred as a result of any user’s reliance on this information. All maps, reports, data, and other information contained herein are protected by copyright. Permission is granted to copy and use the materials herein for any lawful noncommercial purpose. Any user of this information agrees not to transmit or provide access to all or any part of this information to another party unless the user shall include with the information a copy of this disclaimer.
Ordering Instructions: Redwood County’s aggregate resource spatial datasets (shapefiles & file geodatabase) are included in the file redwooddata.zip, accessible from the MN DNR Aggregate Mapping web page: http://www.dnr.state.mn.us/lands_minerals/aggregate_maps/completed/index.html
The spatial datasets include sand and gravel resource potential, geologic field observations, aggregate pits, Minnesota Geological Survey (MGS) County Well Index (CWI) data points, MnDOT Aggregate Source Information System (ASIS) points, and MnDOT ASIS pit quality table
Online Linkage: I AGREE to the notice in "Distribution Liability" above. Clicking to agree will either begin the download process, link to a service, or provide more instructions. See "Ordering Instructions" above for details.

## Section 7: Metadata Reference

Metadata Date: 10/02/2022
Contact Person Information: ,
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Phone:
Email:
Metadata Standard Name: Minnesota Geographic Metadata Guidelines
Metadata Standard Version: 1.2
Metadata Standard Online Linkage: http://www.mngeo.state.mn.us/committee/standards/mgmg/metadata.htm

This page last updated: 10/02/2022
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