SURFICIAL GEOLOGY



Field

Description

Main ID Information

Metadata Updated 2007

Title

Blue Earth County Aggregate Resource Evaluation - Surficial Geology

Filename

Sg99xpy3 (ArcView Shapefile)

Abstract

This dataset consists of information about the geology, geological characteristics, and aggregate potential of 44 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

Blue Earth County, Minnesota

Theme Keywords

Surficial Geology, Geological Characteristics, Potential

Time Period of Content

Summer and Fall 1998

Parent Theme

NA (FIELDOBS)

Spatial Extent of the Data

Blue Earth County, Minnesota

Contact Person

Aggregate Resources Mapping Program

Contact Person Organization/Division

Department of Natural Resources, Division of 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 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 summer and fall of 1998 and compiled in the Fall, Winter, and Spring of 1998-1999.

Maintenance Frequency

None Planned

Access Constraints

NA

Use Constraints

NA

Associated Data Sets

Field Observations (FIELDOBS), Aggregate Resources of Blue Earth 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 over 1,500 water well logs and by observing approximately 450 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 7.2.1

Vendor Specific Object Type

NA

Tiling Scheme

County

Spatial Object Type

Vector-polygon

Transfer Size

8.17 mb

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

SG99XPY3.dbf

Map_unitno

 

Number,3,0

Ex: 100-167.

Unique identifier (Numbers have no significance).

 

Mu_geolabl

 

Text, 8

Ex: PFEG-M

The first letter (P) refers to the age, the second letter (F) refers to the process, the third letter (E) refers to the feature, the forth letter (G) refers to the material, and the fifth (M) refers to the potential.

 

Mu_desc

 

Text, 90

Ex: Glaciofluvial Outwash, Major Terrace Deposit.

A short, summarized description of the mapping units.

 

Surfgeol

 

Text, 32

Ex: Esker, Beach, Till, Terrace, Collapsed Channel, Colluvium, Delta, Flood Plain, Glacial Lake, Kame, Limestone, Sandstone, Outwash Channel, etc.

Describes the type of geological feature that was mapped, mostly glacial features, however also contains bedrock and modern features.

 

Sgprocess

 

Text, 20

Alluvial

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

 

 

 

 

Bedrock

Ordovician and Cambrian age formations such as the Jordan and Oneota Formations deposited by ancient seas advancing and retreating.

 

 

 

 

Glaciofluvial

Glacial Sediments that have been sorted by meltwater.

 

 

 

 

Glaciolacustrine

Glacial Lake Processes.

 

 

 

 

Lacustrine

Modern Lake Processes.

 

 

 

 

Till

Unsorted glacial material deposited in place.

 

Sgfeature

 

Text, 20

Ex: Alluvial Valley, Beach, Bedrock, Channel Ridge, Esker, Fan/Delta, Flood Plain, Glacial Lake, Kame, Moraine, Outwash Channel, or Terrace.

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.

 

Sgmaterial

 

Text, 30

Ex: Sand, Silt, Clay, Gravel, Limestone, Sandstone, Etc...

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

 

Ap_Prob

 

Text, 16

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.

 

Apdepsize

 

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

 

Ap_thick

 

Text, 8

Ex: 0-10, 10-30, >50, 15-50

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

 

Ap_overbrd

 

Text, 8

Ex: 0-10, 0-15, 0-20, 10-15, 30-80

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

 

Ap_texture

 

Text, 16

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.

 

Ap_Quality

 

Text, 16

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 deposits in Blue Earth County are rare, even the best do not always meet MN/DOT specifications for concrete and asphalt.

 

Pot_plate1

 

Text, 8

Highbd

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

The Highbd unit consists of Limestone bedrock units that are moderately desirable.

 

 

 

 

Higher

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

 

 

 

 

Lower

The units with less desirable aggregate deposits or limited deposits.

 

Pot_Plate2

 

Text, 16

High

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

Moderately desirable sand and gravel units

 

 

 

 

Low

Less desirable sand and gravel units

 

 

 

 

Bed Moderate

Moderately desirable limestone units.

 

 

 

 

Bed Lower

Less desirable bedrock units.

 

 

 

 

Slight

Those units with little or no potential for aggregate.

 

Pot_hilo2c

 

Text, 8

Higher

Aggregate Potential : All aggregate resources with highly and moderately desirable potential. Includes moderately and highly desirable sand and gravel and moderately desirable crushed stone.

 

 

 

 

Lower

Aggregate resources with less desirability and limited potential. Includes less desirable sand and gravel and less desirable crushed stone, as well as the limited potential units.

 

Pot_hilo4c

 

Text, 16

Bed Higher

Aggregate Potential: Includes all units that are moderately desirable for crushed stone potential.

 

 

 

 

Bed Lower

Includes all units that are less desirable for crushed stone potential.

 

 

 

 

Higher

Includes all units that are moderately and highly desirable for sand and gravel potential.

 

 

 

 

Lower

Includes all units that are less desirable for sand and gravel potential and all other units with limited potential.

 

Pot_yorn

 

Text, 16

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.

 

Mu_age

 

Text, 16

Holocene

Geological Age Unit. Holocene represents a time period from approximately 10,000 years ago till present.

 

 

 

 

Holocene/Pleist.

Holocene and Pleistocene in age.

 

 

 

 

Pleistocene

Geological time unit ranging from 2.5 million years ago till 10,000 years ago.

 

 

 

 

Ordovician

Geological time unit ranging from 500 to 440 million years ago.

 

 

 

 

Cambrian-Ordov.

Ordovician and Cambrian in age.

 

 

 

 

Ordovician

Geological time unit ranging form 570 to 500 million years ago.

 

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: 2,5,10,15,20,25

Describes the maximum thickness of the aggregate unit.

 

Over_min

 

Number,3,0

Ex: 0,5,10,30

Describes the minimum thickness of the overburden covering the aggregate.

 

Over_max

 

Number,3,0

Ex: 5,10,15,20,50,80

Describes the minimum thickness of the overburden covering the aggregate.