SURFICIAL GEOLOGY - BOUNDARY LINES



Field

Description

Main ID Information

Metadata Updated 2007

Title

Blue Earth County Aggregate Evaluation - Surficial Geology

Filename

Sg99xln3 (ArcView Shapefile)

Abstract

This dataset consists of information about the types of boundary lines found within the surficial geology layer. The five types of lines between mapping units are: the county boundary, geologic contacts, inferred geologic contacts, scarps (channel boundaries), and inferred scarps (channel boundaries).

Place Keywords

Blue Earth County, Minnesota

Theme Keywords

Boundary Lines, Geological Contacts

Time Period of Content

Summer 1998

Parent Theme

NA (SG99XPY3)

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 differentiate the types of geological contacts so that various line symbols (solid, hatched, or dashed) can be used to show these contacts on a map.

Progress

Complete

Currentness Reference

1998-1999

Maintenance Frequency

Non planned

Access Constraints

NA

Use Constraints

NA

Associated Data Sets

Surficial Geology (sg99xpy3.shp and sgsymln3)

Data Quality

 

Attribute Accuracy

These lines were digitized off 1:24,000 topographic maps.

Logical Consistency

Overshoots, undershoots, etc. were fixed by a variety of techniques, thus the lines have been checked and completed.

Completeness

The units were delineated by aerial photograph interpretation (1:40,000), transferred onto 1:24,000 topographic maps, and digitized.

Horizontal Positional Accuracy

1:50000

Vertical Positional Accuracy

NA

Lineage

Color infrared and black-and-white aerial photographs were used to delineate geological landforms and aggregate resources. Stereoscopic pairs of color infrared aerial photographs (NAPP, 9"x9" at 1:40,000 scale, April 1991 and 1992) were used along with reconnaissance-level, high-altitude, black-and-white photographs (1:80,000 scale). Aerial photographs (DOQs) were also available digitally and used within ARCVIEW (1:12,000 scale; Figure 2). Aerial photographic interpretation was completed with a glacial mapping technique known as the landsystems 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 landsystems 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 landsystems approach) was also used when interpreting the topography within Blue Earth County; glacial landforms have distinct and unique shapes and patterns that can be observed in their topographic expression. Topographic maps (USGS 1:24,000), 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, collapsed channels, deltas, kames, eskers, and terraces).

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 that the lines delineate are referenced as geological features.

Native Dataset Environment

ArcView 3.1 / ArcInfo7.2.1

Vendor Specific Object Type

NA

Tiling Scheme

NA

Spatial Object Type

Vector

Transfer Size

4.42 mb

Entities -- Attributes

 

Entity-Attribute Overview

Arcs that delineate polygon features for the surficial geology layer.

Entity-Attribute Detailed Citation

See table below: Arcview specific fields include shape (i.e., feature type - polyline), fnode_ (id of beginning node of line), tnode_ (id of ending node of line), lpoly_ (id of polygon to the left of the line - "0" if a line feature, not a line defining a polygon), rpoly_ (id of polygon to the right of the line - "0" if a line feature, not a line defining a polygon), filename_ (unique id for line, assigned by 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

Sg99xln3.shp

Uniqln_id

 

Number,3,0

1

Blue Earth County Boundary

 

 

 

 

200

Geological contact - well defined

 

 

 

 

201

Geological contact - inferred

 

 

 

 

210

Channel Scarp - well defined

 

 

 

 

211

Channel Scarp - inferred

 

Sgeolntype

 

Text, 30

Blue Earth County Boundary

Descriptions of unique Identifiers

 

 

 

 

Geological contact - well defined

Geological contact - well defined

 

 

 

 

Geological contact - inferred

Geological contact - inferred

 

 

 

 

Channel Scarp - well defined

Channel Scarp - well defined

 

 

 

 

Channel Scarp - inferred

Channel Scarp - inferred