AGGREGATE POTENTIAL - POLYGONS

Field	Description
Main ID Information	Metadata Updated 2007
Title	Benton County Aggregate Resource Evaluation
Filename	Agp02py3 (ArcView Shapefile)
Abstract	This dataset consists of information about the geology, geological characteristics, and aggregate potential of 165 map units. Five fields relate to the surficial geology of the map unit. Twelve fields relate to the sand and gravel characteristics, including probability, quality, texture, overburden thickness, and deposit size, of the map unit. Eleven fields relate to crushed stone characteristics, including probability, quality, overburden thickness, and deposit size, of the map unit. These characteristics were used to calculate the aggregate potential of the map unit for both crushed stone and sand and gravel.
Place Keywords	Benton County, Minnesota
Theme Keywords	Surficial Geology, Geological Characteristics, Aggregate Potential, Sand, Gravel, Crushed Stone
Time Period of Content	Fall 2001 – Spring 2002
Parent Theme	NA (FIELDOBS)
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 summarize the geological characteristics, surficial geology, and aggregate potential (sand, gravel, and crushed stone) 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.
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	Field Observations (FIELDOBS), Aggregate Resources of Benton County, Minnesota
Data Quality
Attribute Accuracy	The sand and gravel and surficial geology 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. The final coverage was digitized on-screen using Digital Orthographic Quads (DOQ 1:12,000 Scale). This was a reconnaissance scale study and was mapped at 1:50,000. The crushed stone units were delineated based on a model used to define a depth to bedrock surface (see the “Lineage” section below for more information.
Logical Consistency	NA
Completeness	The sand and gravel resource 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). The crushed stone resource units were delineated by creating a model of the depth to bedrock (1:100,000).
Horizontal Positional Accuracy	1:50,000 for sand and gravel, 1:100,000 for crushed stone.
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 1,000 water well logs and by observing approximately 1,325 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. 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) were 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	1:50,000 for sand and gravel, 1:100,000 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 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
Entities -- Attributes
Entity-Attribute Overview	Geological Features, Geological Characteristics, and Aggregate Potential.
Entity-Attribute Detailed Citation	ArcView specific fields include shape (i.e., feature type = polygon), area (given in square meters), perimeter (given in meters), Agp02ne3_ (counter field - assigned by the software), and Agp02ne3_i (an id usually assigned during theme creation). The aggregate potential attributes for the polygons are described in the table below.

Table Name	Field Name	Begin Column	Definition	Valid Values	Descriptions
Agp02py3.dbf	Map_unitno		Number,4,0	Ex: 101-3250.	Unique identifier (Combination or adding Sg_mapu and Cs_mapu: Numbers have no significance).
	Surf_desc		Text, 56	Ex: Glaciofluvial Outwash, Outwash Modified Till.	A short, summarized description of the surficial geologic mapping units.
	Sgeo_age		Text, 24	Ex: Holocene, Precambrian, Quaternary, etc.	Describes the age of the material encountered at the surface.
	Sgeo_pl3		Text, 66	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
	Sgeo_proc		Text, 37	Alluvial	The geological process that deposited these features. Alluvial processes are modern stream processes.
				Alluvial over Glaciofluvial	Modern stream processes overlying glaciofluvial (glacial stream) processes
				Bedrock	Precambrian age granitic rocks such as granites and granodiorites that were deposited by volcanic activity. Deposited billions of years ago.
				Eolian	Material that was deposited by wind, usually as dunes.
				Eolian and Glaciofluvial over Glacial	Glacial Till that was modified by glaciofluvial outwash, which was later modified by eolian material. These areas represent patchy and discontinues areas of these three processes, which were too difficult to differentiate at this mapping scale.
				Glacial	Unsorted glacial material deposited in place.
				Glaciofluvial	Glacial sediments that have been sorted by meltwater.
				Glaciofluvial over Glaciolacustrine	Glacial Sediments that have been sorted by meltwater overlying material that was deposited at the bottom of a glacial lake.
				Glaciolacustrine	Sediments that were deposited at the bottom of an ancient glacial lake.
				Lacustrine over Glaciofluvial	Lake sediments overlying glaciofluvial outwash sands and gravels.
	Sgeo_feat		Text, 41	Ex: Alluvial Fan, Alluvial Terrace, Bedrock Outcrop, Beach, Kame, Esker, Flood Plain, etc...	The type of geological feature encountered at the surface (surficial geology). Surficial Geology is defined as the geologic units encountered within the top 5 to 10 feet of the surface.
	Sgeo_mat		Text, 34	Ex: Des Moines Till, Granite, Sand, Sand and Gravel, Silt and Clay, etc…	The dominant type of material encountered in the surficial geologic unit.
	Sg_prob		Text, 17	Very High, High, Moderately High, Moderate, Moderately Low, Low, Very Low.	The relative degree of certainty that sand and gravel exists within a unit. Based on air photo interpretations, field observations, CWI, drilling, presence of gravel pits and quarries, etc. Each unit is relative to the other units and range from very high to very low.
	Sg_depsize		Text, 18	Very Large	Size of the sand and gravel 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
	Sg_thick		Text, 12	Ex: 0-10, <10, >10, 20-50, >50	The assumed range of thickness of the sand and gravel deposit (in feet).
	Sg_ovrbrdn		Text, 16	Ex: 0-10, 0-3,<5, >20, 10-20, 20-50	The assumed range of overburden thickness of a sand and gravel deposit (in feet).
	Sg_texture		Text, 18	Very Good, Good, Moderately Good, Moderate, Moderately Poor, Poor, Very Poor.	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 MN/DOT Pit sheets for more detail.
	Sg_quality		Text, 17	Very Good, Good, Moderately Good, Moderate, Moderately Poor, Poor, Very Poor.	A relative scale of the quality of the sand and gravel (soundness, durability, and mineral makeup). Determined from MN/DOT pit sheets.
	Cs_prob		Text, 15	Very High, High, Moderately High, Low.	The relative degree of certainty that crushed stone exists within a unit. Based on air photo interpretations, field observations, CWI, drilling, presence of gravel pits and quarries, etc. Each unit is relative to the other units and range from very high to very low.
	Cs_depsize		Text, 14	Very Large	Size of the crushed stone deposit (areal extent). Ex: number of acres. A very large deposit would be considered > 50 acres.
				Large	40-50 acres
				Small	5-10 acres
	Cs_thick		Text, 11	Ex: >50	The assumed thickness of the crushed stone (in feet).
	Cs_ovrbrdn		Text, 16	Ex: 0-10, 0-20, 20-30, 30-50, >50.	The assumed range of overburden thickness of a crushed stone deposit (in feet).
	Cs_quality		Text, 14	Very Good and Good	A relative scale of the quality of crushed stone (soundness, durability, and mineral makeup). Determined from MN/DOT pit sheets.
	Sg_pot_pl1		Text, 17	Limited, Sand and Gravel.	Sand and Gravel Potential that is depicted on plate 1 (Significant Aggregate Resources). Sand and Gravel refers to those units that have a high to moderate potential of containing significant sand and gravel deposits. Desirability is determined by the sand and gravel potential attributes (Sg_xxxxx, as described above).
	Sg_pot_pl2		Text, 15	High, Moderate, Low, Limited.	Sand and Gravel Potential that is depicted on plate 2 (Aggregate Resources). High, Moderate, and Low refer to the relative potential of the Sand and Gravel units. Desirability is determined by the sand and gravel potential attributes (Sg_xxxxx, as described above). Limited refers to those units that do not contain sand and gravel or where the deposits are insignificant.
	Cs_pot_pl1		Text, 13	Bedrock, Limited.	Crushed Stone Potential that is depicted on plate 1 (Significant Aggregate Resources). Bedrock refers to those units that have a high to moderate potential of containing significant crushed stone resources. Desirability is determined by the crushed stone potential attributes (Cs_xxxxx, as described above).
	Cs_pot_pl2		Text, 13	High, Moderate, Low, Limited.	Crushed Stone Potential that is depicted on plate 2 (Aggregate Resources). High, Moderate, and Low refer to the relative potential of the Crushed Stone resources. Desirability is determined by the Crushed stone potential attributes (Cs_xxxxx, as described above). Limited refers to those units where the depth to crushed stone is greater than 50 feet.
	Pot_plate1		Text, 28	Sand and Gravel	Aggregate Potential (Sand, Gravel, and Crushed Stone) that is depicted on Plate 1 (Significant Aggregate Resources). Sand and Gravel refers to those units with moderate or high potential of containing significant sand and gravel resources.
				Bedrock	Those units with moderate or high potential of containing significant crushed stone resources.
				Sand and Gravel over Bedrock.	Those units with moderate or high potential of containing significant sand and gravel resources overlying areas with moderate or high potential of containing significant crushed stone resources.
				Limited	Those areas containing low potential sand, gravel, and crushed stone resources, as well as area with limited potential.
	Pot_plate2		Text, 30	Ex: High over Low Bedrock, Low, Moderate, Moderate over High Bedrock.	Aggregate Potential (Sand, Gravel, and Crushed Stone) that is depicted on Plate 2 (Aggregate Resources).
	Sg_min		Number,3,0	Ex: 0,5,10,15,20,50	Describes the minimum thickness of the sand and gravel unit.
	Sg_max		Number,3,0	Ex: 0, 5, 10, 20, 30, 40, 50	Describes the maximum thickness of the sand and gravel unit.
	Sgover_min		Number,3,0	Ex: 0, 10,20	Describes the minimum thickness of the overburden covering the sand and gravel.
	Sgover_max		Number,3,0	Ex: 0, 3, 5, 10, 20, 30	Describes the maximum thickness of the overburden covering the sand and gravel.
	Cs_min		Number,3,0	Ex: 0,5,10,15,20,50	Describes the minimum thickness of the crushed stone unit.
	Cs_max		Number,3,0	Ex: 0, 5, 10, 20, 30, 40, 50	Describes the maximum thickness of the crushed stone unit.
	Csover_min		Number,3,0	Ex: 0, 10,20	Describes the minimum thickness of the overburden covering the crushed stone.
	Csover_max		Number,3,0	Ex: 0, 3, 5, 10, 20, 30	Describes the minimum thickness of the overburden covering the crushed stone.