SURFICIAL GEOLOGY



Field

Description

Main ID Information

Metadata Updated 2007

Title

Nicollet County Aggregate Resource Evaluation - Surficial Geology

Filename

Sg00xpy3 (ArcView Shapefile)

Abstract

This dataset consists of information about the geology, geological characteristics, and aggregate potential of 77 map units. The geology is divided into 4 fields that describe the sources, features, material, and surficial geology unit. The geological characteristics include probability, deposit size, thickness, overburden, texture, and quality. These characteristics were used to calculate the aggregate potential of the unit.

Place Keywords

Nicollet County, Minnesota

Theme Keywords

Surficial Geology, Geological Characteristics, Potential

Time Period of Content

Summer and Fall 1999

Parent Theme

NA (FIELDOBS)

Spatial Extent of the Data

Nicollet County, Minnesota

Contact Person

Aggregate Resource Mapping Program (Geologist or GIS Specialist)
Minnesota Department of Natural Resources, Division of Lands and Minerals
500 Lafayette Road, Box 45

St. Paul, MN 55155-4045
Phone: 651-259-5959
FAX:  651-296-5939
E-mail: AggregateMap@dnr.state.mn.us

Contact Person Organization/Division

Department of Natural Resources, Division of Lands and Minerals

Contact Person Position

Geologist or GIS Specialist

Contact Address

500 Lafayette Road, Box 45

Contact City

St. Paul

Contact Zip Code

55155-4045

Contact Voice Phone

651-259-5959

Contact Fax Phone

651-296-5939

Additional ID Information

 

Originator

Department of Natural Resources, Division of Lands and Minerals, Mineral Potential Section

Purpose

To summarize the geological characteristics, surficial geology, and aggregate potential of the different units. To help catagorize the geological characteristics and incorporate them into a model to help determine the geological potential of the deposit.

Progress

Complete

Currentness Reference

All data was gathered in the fall of 1999 and the spring of 2000 and compiled in the Summer and Fall of 2000.

Maintenance Frequency

None Planned

Access Constraints

NA

Use Constraints

NA

Associated Data Sets

Field Observations (FIELDOBS), Aggregate Resources of Nicollet County Minnesota

Data Quality

 

Attribute Accuracy

The units were delineated by the interpretation of aerial photographs at a 1:40,000 scale. These interpretations were plotted on 1:24,000 USGS topographic maps. These delineations and unit descriptions were field checked and revised. This was a reconnasance scale study and was mapped at 1:50,000.

Logical Consistency

NA

Completeness

The units were delineated by aerial photograph interpretations. The potential of the deposit is based on geological factors and not economical factors. Generalizations were made, this is a reconnaissance scale study (1:50,000)

Horizontal Positional Accuracy

1:50000

Vertical Positional Accuracy

NA

Lineage

The first step in determining the distribution of aggregate resources is to understand the surficial geology and the recent geological history of the area. The geological history basically tells us the story, or sequence of events, of when the aggregate and other sediments were deposited. By understanding this story we can determine where the aggregate was deposited, as well as some of the general characteristics about the material. This was accomplished for this study by completing an aerial photograph interpretation of the entire county and confirming these interpretations with approximately 900 water well logs and by observing approximately 950 field sites. Several other data sets and techniques were also used and are described below. These interpretations and observations were then compiled to form a sequence of events to tell the geologic story. Finally, the aggregate bearing landforms were delineated and categorized based on their geological characteristics.

Source Scale Denominator

1:50000

Spatial Reference

 

Horizontal Coordinate Scheme

UTM

Ellipsoid

GRS80

Horizontal Datum

NAD83

Horizontal Units

Meters

Distance Resolution

NA

Altitude Datum

NA

Altitude Units

NA

Depth Datum

NA

Depth Units

NA

UTM Zone Number

15

Raster only

 

Cell Width

NA

Cell Height

NA

Spatial Data Organization

 

Geographic Reference for Tabular Data

The units are referenced as geological features (glacial drift, bedrock, and modern sediments).

Native Dataset Environment

ArcView 3.1/ArcInfo 8.0.2

Vendor Specific Object Type

NA

Tiling Scheme

County

Spatial Object Type

Vector-polygon

Transfer Size

4541 kb

Entities -- Attributes

 

Entity-Attribute Overview

Geological Features, Geological Characteristics, and Aggregate Potential.

Entity-Attribute Detailed Citation

See table below: Arcview specific fields include shape (i.e., feature type = polygon), area (given in square meters), perimeter (given in meters), filename_ (unique id for polygon, assigned by the software), filename_i or filename_id if filename is less than 8 characters (an id usually assigned during theme creation).





Table Name

Field Name

Begin Column

Definition

Valid Values

Descriptions

SG00XPY3.dbf

Map_unitno

 

Number,3,0

Ex: 101-850.

Unique identifier (Numbers have no significance).

 

Descriptio

 

Text, 58

Ex: Glaciofluvial Outwash, Major Terrace Deposit.

A short, summarized description of the mapping units.



Age

 

Text, 20

Ex: Cretaceous, Holocene, Pleistocene, Ordovician, Cambrian, Precambrian, etc.

Describes the age of the material encountered.



Sg_plate3

 

Text, 75

Ex: Alluvial Fan Sediments, Alluvial Terrace Sediments, Glaciofluvial Fan Sediments, etc.

Describes the surficial geologic unit. It may be a bedrock material, a glacial sediment, or a modern Holocene sediment

 

Process

 

Text, 20

Alluvial

The geological process that deposited these features. Alluvial processes are modern stream processes.

 

 

 

 

Bedrock

Cambrian age formations such as the Jordan Sandstone or St. Lawrence Formations deposited by ancient seas advancing and retreating.



 

 

 

Colluvial

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

 

 

 

 

Glacial

Unsorted glacial material deposited in place.

 

 

 

 

Glaciofluvial

Glacial Sediments that have been sorted by meltwater.

 

 

 

 

Lacustrine

Modern Lake Processes.

 

 

 

 

Man-made

A man made holding pond/sediment pool.

 

Feature

 

Text, 20

Ex: Alluvial Fan, Alluvial Terrace, Bedrock, Colluvium, Drainage Pond, Esker, Floodplain, etc...

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

 

Material

 

Text, 28

Ex: Gneiss, Kaolin, Sand, Gravel, Clay, Limestone, Etc...

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

 

Probabilit

 

Text, 15

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

The relative degree of certainty that aggregate exists within a unit. Based on air photo interpretations, field observations, CWI, drilling, presence of gravel pits and quarries, etc... Relative to each other ranging from very high to very low.

 

Dep_size

 

Text, 16

Very Large

Size of the aggregate deposit (areal extent). Ex: number of acres. A very large deposit would be considered > 50 acres.

 

 

 

 

Large

40-50 acres

 

 

 

 

Moderately Large

30-40 acres

 

 

 

 

Moderate

20-30 acres

 

 

 

 

Moderately Small

10-20 acres

 

 

 

 

Small

5-10 acres

 

 

 

 

Very Small

< 10 acres

 

Thickness

 

Text, 5

Ex: 0-10, <10, >10, 20-50, >50

The assumed range of thickness of an aggregate deposit (in feet).

 

Overburden

 

Text, 5

Ex: 0-10, 0-3,<5, >20, 10-20, 20-50

The assumed range of overburden thickness of an aggregate deposit (in feet).

 

Texture

 

Text, 15

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

A relative scale of the textural quality of the aggregate 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, 15

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

A relative scale of the quality of the aggregate resources (soundness, durability, and mineral makeup). Determined from MN/DOT pit sheets. Very Good Quality Sand and Gravel deposits in Nicollet County are rare, even the best do not always meet MN/DOT specifications for concrete and asphalt.

 

Pot_plate1

 

Text, 15

Bedrock

Defines the Aggregate Potential as 3 units: the best aggregate deposits (those most desirable) and the less desirable deposits.

The aggregate units that are either moderately or highly desirable for crushed stone potential.

 

 

 

 

Sand and Gravel

The aggregate units with either moderate or highly desirable sand and gravel deposits.

 

 

 

 

Limited

The units with less desirable aggregate deposits or limited deposits.

 

Pot_Plate2

 

Text, 24

High sand and gravel

These units with highly desirable sand and gravel deposits. Desirability is determined by the aggregate potential parameters (ap_xxxxx, as described above).

High refers to highly desirable sand and gravel units.

 

 

 

 

Moderate sand and gravel

Moderately desirable sand and gravel units

 

 

 

 

Low sand and gravel

Less desirable sand and gravel units

 

 

 

 

High bedrock

Highly desirable bedrock units (Sioux Quartzite).

 

 

 

 

Moderate bedrock

Moderately desirable bedrock units (Sioux Quartzite, Granitic Gneisses, Limestones).

 

 

 

 

Low bedrock

Less desirable bedrock units (limestone).

 

 

 

 

Limited

Those units with little or no potential for aggregate.

 

Pot_yorn

 

Text, 9

Potential

All aggregate resources (sand, gravel, and crushed stone) that have potential. Includes highly, moderately, and less desirable aggregate resources.

 

 

 

 

Limited

Those units with limited potential. No identified significant aggregate resources.

 

Pot_4class

 

Text, 8

High

Aggregate Potential: All units that have highly desirable aggregate resources.

 

 

 

 

Moderate

All units that have moderately desirable aggregate resources.

 

 

 

 

Low

All units that have less desirable aggregate resources.

 

 

 

 

Limited

All units that have limited potential for aggregate resources.

 

Aggr_min

 

Number,3,0

Ex: 0,5,10,15,20,50

Describes the minimum thickness of the aggregate unit.

 

Aggr_max

 

Number,3,0

Ex: 0, 5, 10, 20, 30, 40, 50

Describes the maximum thickness of the aggregate unit.

 

Over_min

 

Number,3,0

Ex: 0, 10,20

Describes the minimum thickness of the overburden covering the aggregate.

 

Over_max

 

Number,3,0

Ex: 0, 3, 5, 10, 20, 30

Describes the minimum thickness of the overburden covering the aggregate.