AGGREGATE POTENTIAL - BOUNDARY LINES

Field	Description
Main ID Information	Updated 2007
Title	Benton County Aggregate Evaluation
Filename	Agp02ln3 (ArcView Shapefile)
Abstract	This dataset consists of information about the types of boundary lines found within the aggregate potential layer. The five types of lines between mapping units are: the County border, Geologic Contact (inferred), Geologic Contact (Well Defined), Channel Scarp (Inferred), and Channel Scarp (Well Defined).
Place Keywords	Benton County, Minnesota
Theme Keywords	Boundary Lines, Geological Contacts
Time Period of Content	Fall 2001 and Spring 2002
Parent Theme	NA (Agp02py3)
Spatial Extent of the Data	Benton County, Minnesota
Contact Person	Aggregate Resources Mapping Program
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 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	All data was gathered in the late fall of 2000 and the summer and fall of 2001 and compiled in the Fall of 2001 through the spring of 2002.
Maintenance Frequency	None planned
Access Constraints	NA
Use Constraints	NA
Associated Data Sets	Aggregate Potential and Surficial Geology (Agp02py3 and sgeoxln3)
Data Quality
Attribute Accuracy	The lines delineating the sand and gravel resources and surficial geology were digitized on screen with DOQs (1:12000 USGS Digital Orthophotoquadrangles) and DRGs (1:24000 USGS scanned topographic maps – digital raster graphics) as the backdrops. The lines delineating the crushed stone resources were based on a model to define a depth to bedrock surface (see the “Lineage” section below for additional information).
Logical Consistency	Overshoots, undershoots, etc. were fixed by a variety of techniques, thus the lines have been checked and completed.
Completeness	The sand and gravel resource units were delineated by aerial photograph interpretation (1:40,000), and digitized on screen using ARCVIEW; with DOQs and DRGs (topographic maps) as the backdrops. The crushed stone resource units were delineated by creating a model of the depth to bedrock.
Horizontal Positional Accuracy	1:50000 for sand and gravel, 1:100000 for crushed stone
Vertical Positional Accuracy	NA
Lineage	For sand and gravel: 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). 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 Benton 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, glaciofluvial fans, eskers, and terraces). For crushed stone: A model was developed using Arcview and its Spatial Analyst extension to determine the depth to bedrock. The data incorporated into the model included well locations with well log information indicating a depth to bedrock; outcrops from the soil information; outcrops observed in the field; and surface elevations, stored as digital elevation model (30-meter DEM data from USGS). To calculate the depth to bedrock in relation to the surface elevation, the point locations for depth to bedrock and outcrops (i.e., the depth to bedrock equals 0 for outcrops) was subtracted from the surface elevations. A “top of bedrock” surface for the county was then created by interpolating these points. These “top of bedrock” values were then subtracted from the surface elevations, resulting in an approximate depth to crushed stone resource values for the county.
Source Scale Denominator	1:50000 for sand and gravel and 1:100000 for crushed stone
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 / ArcInfo 8.0.2
Vendor Specific Object Type	NA
Tiling Scheme	NA
Spatial Object Type	Vector
Transfer Size
Entities -- Attributes
Entity-Attribute Overview	Arcs that delineate polygon features for the aggregate potential layer.
Entity-Attribute Detailed Citation	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), length (length of the line segment), agp02ne3_ (unique id for line, assigned by Arc/INFO software), agp02ne3_i (an id usually assigned during theme creation). The aggregate potential line attributes are described in the table below.

Table Name	Field Name	Begin Column	Definition	Valid Values	Descriptions
Agp02ln3.shp	Uniqln_id		Number,3,0	1	Benton County Boundary
				261	Geological contact - well defined
				262	Geological contact – inferred
				265	Channel Scarp - well defined
				266	Channel Scarp - inferred
	Agplntype		Text, 33	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