AGGREGATE POTENTIAL:  For the purpose of this project, aggregate potential is defined as an assessment of the relative 
probability that an aggregate deposit exists within a given area, with almost all emphasis placed upon geologic evidence, 
parameters, and interpretation at the reconnaissance level, rather than upon economic feasibility evaluation or other parameters.  
This assessment does not imply that economic aggregate deposits exist everywhere within a given map unit designated as 
"Potential Sand and Gravel Resources" or "Potential Crushed Stone Resources."  Rather, that within such a map unit, geologic 
processes were active that could have created aggregate deposits at specific sites.  Geologic measurements of aggregate deposits 
remain constant, but economic criteria and environmental permitting vary across time and place.  Important site-specific factors, 
such as ownership, zoning, protected waters and wetlands, environmental permitting, distance to markets, royalties, and 
individual site characteristics, such as access, all contribute to the final "potential" of a specific parcel; however, these 
factors were not included in this study.

POTENTIAL SAND AND GRAVEL RESOURCES:  Geologic units that are inferred to contain moderately to highly 
desirable sand and gravel deposits.  The units in this category exhibit the geologic characteristics that typically 
contain sand and gravel deposits.  Existing gravel pits and MN/DOT aggregate sources lying within these units 
indicate identified or known resources.  The geologic units having potential for sand and gravel include alluvial 
features (flood plains, terraces, and fans) and glacial outwash features (channels and terraces).  These units 
typically contain sorted sand and gravel with little silt or clay.

POTENTIAL CRUSHED STONE RESOURCES:  Bedrock formations that consist of moderately and highly desirable 
limestone that is suitable for crushing.  The units are inferred to be thick (greater than 40 feet), with an overburden 
thickness of less than 30 feet.  Quarries located within these units indicate identified or known resources.  These 
bedrock units are most commonly found at or near the surface and along stream cuts in the eastern portion of 
the county.

LIMITED POTENTIAL FOR AGGREGATE RESOURCES:  Units that generally have less desirable, or little or no 
potential for aggregate resources.  These units exhibit geologic characteristics that are typically not consistent with 
significant aggregate deposits.  The geologic units that have less desirable potential typically have thicknesses less 
than 25 feet and overburden thicknesses sometimes reaching greater than 100 feet.  The geologic units include 
alluvial features (beaches and flood plains), glacial outwash features (outwash channels, fans, and deltas), and 
ice-contact features (eskers and kames) that are typically small, thin, or have too fine of a material to be of 
commercial value.  The geologic units having limited potential include eolian (wind-blown), lacustrine (lake plains), 
morainic (till), small alluvial deposits, and bedrock with overburden thicknesses greater than 30 feet.  These units 
typically contain clay, silt, fine sand, unsorted sediments (specifically in till), or very thin layers of sand and gravel.  
The units may include aggregate deposits that are too small to be mapped.


IDENTIFIED AGGREGATE RESOURCES:  Areas where aggregate resources (sand, gravel, and/or crushed stone) have been or 
are currently being mined.  Pit and quarry locations have been gathered from several different reference sources, including 
topographic maps, aerial photographs, county records, county highway department maps, soil surveys, MN/DOT files, fieldwork, 
gravel operators, and other miscellaneous sources.  The pits and quarries range in size from less than 1 acre to greater than 
50 acres and may be active, inactive, depleted, or reclaimed.  The aggregate quality of the pits varies.

Gravel Pits:  Locations were gathered from several different reference sources.  Any given pit may be active, 
inactive, depleted, or reclaimed.

Gravel Pits - MN/DOT files:  Locations gathered from the Minnesota Department of Transportation's Aggregate 
Source Information System (ASIS) listing of aggregate sources.  Test hole logs, sieve, and quality test data 
are available.

Quarries:  Limestone quarries from several different reference sources.  Any given quarry may be active, inactive, 
depleted, or reclaimed.



OTHER FEATURES:
WETLANDS:  Wetland area.

WATER:  Lakes or rivers.

