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 sand and gravel.  These units exhibit the 
geologic characteristics that typically produce sand and gravel deposits.  Existing gravel pit 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, fans) and glacial outwash features (channels and terraces).  These units typically contain sorted 
sand and gravel with little silt or clay.
HIGHLY DESIRABLE SAND AND GRAVEL DEPOSITS:  Fluvial deposits, such as alluvium, alluvial fans, and floodplains, 
and glaciofluvial deposits, such as outwash terraces and channels.  These deposits are moderately large to very large in 
areal extent(1).  These deposits consist of sand and gravel with thicknesses typically ranging from 20 to 50 feet with less 
than 5 feet of overburden.  The probability(2) that a potential sand and gravel deposit exists within this unit is high to very 
high.  The textural characteristics(3) of these deposits are moderately good to good.  The quality(4) ranges from moderately 
high to high relative to all deposits within Dodge County.
MODERATELY DESIRABLE SAND AND GRAVEL DEPOSITS:  Fluvial deposits, such as alluvial terraces and floodplains, 
and glaciofluvial deposits, such as outwash terraces and channels.  These deposits are moderate to large in areal extent 
with sand and gravel thicknesses typically ranging from 10 to 50+ feet with less than 10 feet of overburden.  The 
probability that a potential sand and gravel deposit exists within this unit is moderately high to high.  The textural 
characteristics of these deposits are moderately good to good with the quality ranging from moderately high to high.
LESS DESIRABLE SAND AND GRAVEL DEPOSITS:  Glaciofluvial features, such as fans, deltas, channels, and terraces; 
ice-contact features, such as eskers and lake plains; and alluvial features such as flood plains, terraces, and fans.  These 
deposits are moderately small to very large in areal extent and consist of sand and fine sand with thicknesses ranging 
from 0 to 25 feet with overburden thicknesses between 0 to 25 feet.  The probability that a potential sand and gravel 
deposit exists within this unit is moderate to very high.  The textural characteristics of these deposits are moderately 
poor to moderately good with the quality ranging from moderate to high.

POTENTIAL CRUSHED STONE RESOURCES:  Limestone bedrock formations suitable for producing crushed stone.  These units are 
inferred to be thick (20 to 100+ feet), with overburden thickness of less than 40 feet.  Quarries located within these units indicate 
identified or known resources.
HIGHLY DESIRABLE CRUSHED STONE DEPOSITS:  Limestone bedrock units that are identified as Prosser/Stewartville 
members of the Galena Formation.  These units are greater than 40 feet thick, with overburden thickness of less than 
20 feet.  The quality of these units is good, with mostly massive bedding containing very thin to thin shale partings every
6 inches to 2 feet.
MODERATELY DESIRABLE CRUSHED STONE DEPOSITS:  Limestone bedrock units that are identified as Prosser/
Stewartville members of the Galena Formation.  These units are greater than 40 feet thick, with overburden thickness 
ranging from 20 to 30 feet. The quality of this unit is good, with mostly massive bedding containing very thin to thin shale 
partings every 6 inches to 2 feet.
LESS DESIRABLE CRUSHED STONE DEPOSITS:  Limestone bedrock units that are identified as Prosser/Stewartville 
and Cummingsville members of the Galena Formation.  The Prosser/Stewartville member ranges from 0 to 40+ feet 
thick, with overburden thickness ranging from 30 to 40 feet.  The quality of this unit is good, with mostly massive bedding 
containing very thin to thin shale partings every 6 inches to 2 feet.  The Cummingsville member is no greater than 75 feet 
thick, with overburden thickness ranging from 0 to 20 feet.  The quality of this limestone is moderately poor because it 
contains beds of shale that are 2 inches to 2 feet thick.

LIMITED POTENTIAL FOR AGGREGATE RESOURCES:  Units that generally have little or no potential for significant aggregate 
resources.  These units exhibit geologic characteristics that are typically not consistent with significant aggregate deposits.  The 
geologic units having limited potential include glacial lake plains, moraines, small alluvial deposits, or bedrock with overburden 
thicknesses greater than 50 feet.  These units typically contain clay, silt, fine sand, unsorted sediments (till), or very thin layers of 
sand and gravel.  These units may include aggregate deposits that are too small to map.
LIMITED POTENTIAL FOR AGGREGATE DEPOSITS:  Units that include glacial features such as collapsed glaciofluvial 
channels, till plains, moraines, glacial lake beds, and small alluvial features such as flood plains and streams.  The 
probability that a potential aggregate deposit exists within this unit is very low to moderate.  The aggregate deposits 
occurring in this unit are moderate to very small in areal extent and typically consist of finer material (sand with some 
gravel).  The thickness of these aggregate deposits are typically less than 25 feet, with overburden thicknesses sometimes 
reaching over 100 feet.  The textural characteristics are poor to moderate with the quality ranging from low to moderate.  
These units also contain bedrock units with an overburden thickness of greater than 50 feet.

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 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.  Some quarries near the Mantorville area started as gravel pits and expanded as quarries.  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.  The color indicates the relative size of the pit.
Large - larger than 10 acres.
Medium - larger than a few acres.
Small - less than an acre.

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.  The 
color indicates the relative size of the pit.
Large - larger than 10 acres.
Medium - larger than a few acres.
Small - less than an acre.

Quarries:  Limestone quarries.  Any given quarry may be active, inactive, depleted, or reclaimed.


OTHER FEATURES:
WETLANDS:  Wetland area.

WATER:  Lakes or rivers.


(1) Areal Extent - the size, horizontal extent, or distribution of a unit (e.g., area in acres).
(2) Probability - the degree of certainty that aggregate exists within a mapping unit.
(3) Textural Characteristics - particle size distribution - the percent of gravel or sand vs. silt or clay (e.g., sieve analysis).
(4) Quality - the characteristics of the material - soundness (e.g., magnesium sulfate test), durability (Los Angeles rattler 
  test), and mineral makeup (percent deleterious material such as shale, iron oxide, and unsound chert).
