Chapter WN

COAL RESOURCES, WILLISTON BASIN

By M.S. Ellis,1 G.L. Gunther,2 A.M. Ochs,2 C.W. Keighin,1 G.E.Goven,3

J.H. Schuenemeyer,

1

 H.C. Power,

3

 G.D. Stricker,1 and Dorsey Blake1

in U.S. Geological Survey Professional Paper 1625-A

1 U.S. Geological Survey

2 Consultant, U.S. Geological Survey, Denver, Colorado

3

 North Dakota Geological Survey, Bismarck, North Dakota 
WN-ii

Contents

Coal Resources—Harmon Coal Zone, Bowman-Dickinson Coalfield, Williston

Basin, North Dakota.......................................................................................... WN-1

Harmon Coal Zone Resource Estimates—An Overview ............................ WN-1

Harmon Coal Zone Coal Resources ............................................................ WN-2

Confidence Limits for Harmon Coal Zone Coal Resources........................ WN-4

Coal Resources—Hansen Coal Zone, Bowman-Dickinson Coalfield, Williston

Basin, North Dakota.......................................................................................... WN-6

Hansen Coal Zone Resource Estimates—An Overview.............................. WN-6

Hansen Coal Zone Coal Resources.............................................................. WN-7

Confidence Limits for Hansen Coal Zone Coal Resources......................... WN-9

Coal Resources—Beulah-Zap Coal Zone, Beulah Coalfield, Williston Basin,

North Dakota .................................................................................................. WN-11

Beulah-Zap Coal Zone Resource Estimates—An Overview..................... WN-11

Beulah-Zap Coal Zone Coal Resources..................................................... WN-12

Confidence Limits for Beulah-Zap Coal Zone Coal Resources................ WN-14

Coal Resources—Hagel Coal Zone, Center-Falkirk Coalfield, Williston Basin,

North Dakota................................................................................................... WN-16

Hagel Coal Zone Resource Estimates—An Overview.............................. WN-16

Hagel Coal Zone Coal Resources.............................................................. WN-17

Confidence Limits for Hagel Coal Zone Coal Resources.......................... WN-19

References Cited ............................................................................................. WN-21
WN-iii

Figures

WN-1 Location of 7.5-minute quadrangle maps in the Harmon study limit.

WN-2 Federal coal and surface ownership in the Harmon study limit.

WN-3 Harmon net coal isopach map and resource area.

WN-4 Harmon overburden isopach map.

WN-5 Location of 7.5-minute quadrangle maps in the Harmon study limit.

WN-6 Federal coal and surface ownership in the Hansen study limit.

WN-7 Hansen net coal isopach map and resource area.

WN-8 Hansen overburden isopach map.

WN-9 Location of 7.5-minute quadrangle maps in the Beulah-Zap study limit.

WN-10 Federal coal and surface ownership in the Beulah-Zap study limit.

WN-11 Beulah-Zap net coal isopach map and resource area.

WN-12 Beulah-Zap overburden isopach map.

WN-13 Location of 7.5-minute quadrangle maps in the Hagel study limit.

WN-14 Federal coal and surface ownership in the Hagel study limit.

WN-15 Hagel net coal isopach map and resource area.

WN-16 Hagel overburden isopach map.

Tables

WN-1 Coal resources of the Harmon coal zone in the Bowman-Dickinson

coalfield, Williston Basin, reported by county, overburden, net coal

thickness, and reliability categories

WN-2 Coal resources of the Harmon coal zone in the Bowman-Dickinson

coalfield, Williston Basin, reported by 7.5-minute quadrangle map area
WN-iv

Tables—continued

WN-3 Harmon coal resources in the Bowman-Dickinson coalfield, Williston

Basin, reported by Federal coal and surface ownership

WN-4 Key to 7.5-minute quadrangle maps in the Harmon study limit

WN-5 Data used for computation of confidence limits intervals with reliability

categories for Harmon coal resources

WN-6 Estimates of uncertainty with measurement error for Harmon coal

resources

WN-7 Coal resources of the Hansen coal zone in the Bowman-Dickinson

coalfield, Williston Basin, reported by county, overburden, net coal

thickness, and reliability categories

WN-8 Coal resources of the Hansen coal zone in the Bowman-Dickinson

coalfield, Williston Basin, reported by 7.5-minute quadrangle map area

WN-9 Hansen coal resources in the Bowman-Dickinson coalfield, Williston

Basin, reported by Federal coal and surface ownership

WN-10 Key to 7.5-minute quadrangle maps in the Hansen study limit

WN-11 Data used for computation of confidence limits intervals with reliability

categories for Hansen coal resources

WN-12 Estimates of uncertainty with measurement error for Hansen coal

resources

WN-13 Coal resources of the Beulah-Zap coal zone in the Beulah coalfield,

Williston Basin, reported by county, overburden, net coal thickness, and

reliability categories

WN-14 Coal resources of the Beulah-Zap coal zone in the Beulah coalfield,

Williston Basin, reported by 7.5-minute quadrangle map area
WN-v

Tables—continued

WN-15 Beulah-Zap coal resources in the Beulah coalfield, Williston Basin,

reported by Federal coal and surface ownership

WN-16 Data used for computation of confidence limits intervals with reliability

categories for Beulah-Zap coal resources

WN-17 Estimates of uncertainty with measurement error for the Beulah-Zap coal

resources

WN-18 Coal resources of the Hagel coal zone in the Center-Falkirk coalfield,

Williston Basin, reported by county, overburden, net coal thickness, and

reliability categories

WN-19 Coal resources of the Hagel coal zone in the Center-Falkirk coalfield,

Williston Basin, reported by 7.5-minute quadrangle map area

WN-20 Hagel coal resources in the Center-Falkirk coalfield, Williston Basin,

reported by Federal coal and surface ownership

WN-21 Data used for computation of confidence limits intervals with reliability

categories for Hagel coal resources

WN-22 Estimates of uncertainty with measurement error for Hagel coal resources
WN-1

COAL RESOURCES—HARMON COAL ZONE, BOWMANDICKINSON COALFIELD, WILLISTON BASIN, NORTH

DAKOTA

HARMON COAL ZONE RESOURCE ESTIMATES—AN OVERVIEW

• Coal resources are calculated using the specific gravity of the coal calculated

from apparent coal rank, which is the weight of coal per unit volume, net coal

thickness, and areal extent of the coal.

• Resource tables for the Harmon coal zone in the Bowman-Dickinson coalfield

include coal and overburden thickness categories from Wood and others (1983),

which are based on apparent coal rank. Resources are also reported by county,

Federal coal and surface ownership categories, and 7.5-minute quadrangle.

• Following USGS published guidelines (Wood and others, 1983); coal resource

estimates are divided into measured, indicated, and inferred categories

according to relative abundance and reliability of data.

• Where data are widely spaced a hypothetical resource may be extrapolated.

• Measured resources are tonnage estimates of coal in the coal zone within a

radius of 0.25 mi of a control point where the net thickness of coal is measured.

• Indicated resources are tonnage estimates of coal that is within a radius of 0.25-

0.75 mi of a control point where the net thickness of the coal is measured.

• Inferred resources are tonnage estimates of coal that is within a radius of 0.75-3

mi of a control point where the net thickness of the coal is measured.
WN-2

• Hypothetical resources are tonnage estimates of coal that is beyond a radius of 3

mi of a control point where the net thickness of coal is measured.

• These resource categories assume a high to low degree of geologic assurance.

A statistical method that measures levels of uncertainty (confidence limits) for

the Harmon resource estimates in the Bowman-Dickinson coalfield is also

included in this study.

• Resource estimates are reported in millions of short tons with two significant

figures.

HARMON COAL ZONE COAL RESOURCES

The lateral extent (study Limit) of the Harmon coal zone is defined by the

Montana/North Dakota State line to the west and the eastern edge of Hettinger and

Adams Counties to the east. The northern and southern study extents were based

on paleodrainages (erosional and non-depositional “want” areas) modified from

Cherven and Jacob (1985) and Rehbein (1977). The entire study area is about

2,936,000 acres (1,188,159 hectares) in size.

Harmon coal resources in the Bowman-Dickinson coalfield, in the Williston Basin

of North Dakota were calculated using several software packages and custom

programs. Details of the resource calculation methodology are given in Ellis and

others (1999, in press).

To calculate the Harmon coal resources data were compiled in a StratiFact* (GRG

Corporation, 1996) relational database. Coal beds that made up the Harmon coal

zone were correlated in the database. A custom program was used to calculate net

coal thickness at each data point (drill hole or measured section) location.
WN-3

The net coal thickness and overburden were gridded, and isopach maps were

produced using EarthVision* (Dynamic Graphics, Inc., 1997) software. The grids

were made using an isopach grid option (special handling of 0 values and

terminated data) with a grid spacing of 150 x 150 meters.

The spatial parameters for querying the coal resources (for example, 7.5-minute

quadrangle map (fig. WN-1) area (U.S. Geological Survey National Mapping

Division, unpublished data, undated), Federal coal and surface ownership (fig.

WN-2) (Office of Surface Mining, unpublished data, undated), and reliability, net

coal thickness (fig. WN-3), and overburden (fig. WN-4) categories) were created

on individual layers as ARC/INFO* (ESRI, 1998a) polygon coverages. The

coverages were unioned to make one polygon coverage with many attributes for

each polygon. The polygons in the union coverage were edited in ARC/INFO* and

ArcView* (ESRI, 1998b).

Coal resources were calculated using the EarthVision* (EV) volumetrics tool,

which calculates tonnages in each polygon in the union coverage using the net coal

thickness grid, the area of each polygon, and a conversion factor of 1,750 short

tons per acre-ft for lignite rank coal (Wood and others, 1983). Data from the EV

volumetrics report and the union coverage polygon attribute table were combined

in Excel* (Microsoft, 1997) spreadsheet software. Data for polygons containing

Harmon mines (fig. WN-3) or areas of net coal less than 2.5 ft in thickness were

deleted from the data set. Resource tables were created using data from the

remaining polygons (see tables WN-1, WN-2, and WN-3). The final resource area

(fig. WN-3) (area that met all coal resource criteria) was about 2,586,000 acres

(1,046,519 hectares) in size.

*Commercial software package
WN-4

CONFIDENCE LIMITS FOR HARMON COAL ZONE COAL

RESOURCES

A confidence interval is a statistic designed to capture uncertainty associated with

a point estimate. In this study we computed 90-percent confidence intervals on the

volume (total resource in millions of short tons) of coal in the Harmon coal zone in

the measured, indicated, inferred, and hypothetical categories.

The three main potential sources of error that might bias the confidence intervals

are preferential sampling, measurement errors, and model fitting. The probabilistic

interpretation of a confidence interval is based upon a random sample, which does

not apply in this situation, because there is preferential sampling in those areas

deemed to be minable. Measurement error can be caused by an error in recording

the coal bed thickness or in the definition of coverage areas. Modeling fitting

variability and bias result from the choice of models and fitting procedures.

Confidence limits for coal resources of the Harmon coal zone in the BowmanDickinson coalfield, Williston Basin, North Dakota were calculated by J.H.

Schuenemeyer and H.C. Power. The data set that they used contained net coal

measurements from 348 locations. This data set only included locations that

contained Harmon coal (no 0 net coal thickness values) and data that were

representative of the entire coal zone (no terminated holes).

The confidence limits were derived through a complex series of steps. These steps

included modeling coal thickness trends and removing the coal thickness trends

using a nonparametric regression algorithm called loess (with span=0.5), using

residual thickness to compute a semivariogram, and fitting the semivariogram to an

exponential model. Parameter estimates were sill=26.65 ft2, nugget=3.67 ft2, and
WN-5

range=18.62 miles. Standard deviations of coal thickness were obtained from the

semivariogram model. Differences in point densities were compensated for by

calculating sample size, called a pseudo n, within each reliability category and

calculating the variability of volume for each of the reliability categories.

Volumes of Harmon coal were then calculated at a 90-percent confidence interval

with measurement error. Some of the parameters used and results of the

confidence interval calculations are shown in tables WN-5 and WN-6. A detailed

description of the methodology used is given in Schuenemeyer and Power (in

press) and in Ellis and others (1999, in press).
WN-6

COAL RESOURCES—HANSEN COAL ZONE, BOWMANDICKINSON COALFIELD, WILLISTON BASIN, NORTH

DAKOTA

HANSEN COAL ZONE RESOURCE ESTIMATES—AN OVERVIEW

• Coal resources are calculated using the specific gravity of the coal calculated

from apparent coal rank, which is the weight of coal per unit volume, net coal

thickness, and areal extent of the coal.

• Resource tables for the Hansen coal zone in the Bowman-Dickinson coalfield

include coal and overburden thickness categories from Wood and others (1983),

which are based on apparent coal rank. Resources are also reported by county,

Federal coal and surface ownership categories, and 7.5-minute quadrangle.

• Following USGS published guidelines (Wood and others, 1983); coal resource

estimates are divided into measured, indicated, and inferred categories

according to relative abundance and reliability of data.

• Where data are widely spaced a hypothetical resource may be extrapolated.

• Measured resources are tonnage estimates of coal in the coal zone within a

radius of 0.25 mi of a control point where the net thickness of coal is measured.

• Indicated resources are tonnage estimates of coal that is within a radius of 0.25-

0.75 mi of a control point where the net thickness of the coal is measured.

• Inferred resources are tonnage estimates of coal that is within a radius of 0.75-3

mi of a control point where the net thickness of the coal is measured.
WN-7

• Hypothetical resources are tonnage estimates of coal that is beyond a radius of 3

mi of a control point where the net thickness of coal is measured.

• These resource categories assume a high to low degree of geologic assurance.

A statistical method that measures levels of uncertainty (confidence limits) for

the Hansen resource estimates in the Bowman-Dickinson coalfield is also

included in this study.

• Resource estimates are reported in millions of short tons with two significant

figures.

HANSEN COAL ZONE COAL RESOURCES

The lateral extent (study limit) of the Hansen coal zone is defined by the

Montana/North Dakota State line to the west and the eastern edge of Hettinger and

Adams Counties to the east. The Hansen study area was divided into pods and

bounded to the north and to the southwest, based paleodrainages (erosional and

non-depositional “want” areas) modified from Cherven and Jacob (1985) and

Rehbein (1977). The southeast boundary is defined by the North Dakota/South

Dakota State line. The entire study area is about 1,728,000 acres (699,298

hectares) in size.

Hansen coal resources in the Bowman-Dickinson coalfield, in the Williston Basin

of North Dakota were calculated using several software packages and custom

programs. Details of the resource calculation methodology are given in Ellis and

others (1999, in press).

To calculate the Hansen coal resources data were compiled in a StratiFact* (GRG

Corporation, 1996) relational database. Coal beds that made up the Hansen coal
WN-8

zone were correlated in the database. A custom program was used to calculate net

coal thickness at each data point (drill hole or measured section) location.

The net coal thickness and overburden were gridded, and isopach maps were

produced using EarthVision* (Dynamic Graphics, Inc., 1997) software. The grids

were made using an isopach grid option (special handling of 0 values and

terminated data) with a grid spacing of 150 x 150 meters.

The spatial parameters for querying the coal resources (for example, 7.5-minute

quadrangle (fig. WN-5) map area (U.S. Geological Survey National Mapping

Division, unpublished data, undated), Federal coal and surface ownership (fig.

WN-6) (Office of Surface Mining, unpublished data, undated), and reliability, net

coal thickness (fig. WN-7), and overburden (fig. WN-8) categories) were created

on individual layers as ARC/INFO* (ESRI, 1998a) polygon coverages. The

coverages were unioned to make one polygon coverage with many attributes for

each polygon. The polygons in the union coverage were edited in ARC/INFO* and

ArcView* (ESRI, 1998b).

Coal resources were calculated using the EarthVision* (EV) volumetrics tool,

which calculates tonnages in each polygon in the union coverage using the net coal

thickness grid, the area of each polygon, and a conversion factor of 1,750 short

tons per acre-ft for lignite rank coal (Wood and others, 1983). Data from the EV

volumetrics report and the union coverage polygon attribute table were combined

in Excel* (Microsoft, 1997) spreadsheet software. Data for polygons containing

Hansen mines (fig. WN-7) or areas of net coal less than 2.5 ft in thickness were

deleted from the data set. Resource tables were created using data from the

remaining polygons (tables WN-7, WN-8, and WN-9). The final resource area
WN-9

(fig. WN-7) (area that met all coal resource criteria) was about 1,655,000 acres

(669,756 hectares) in size.

*Commercial software package

CONFIDENCE LIMITS FOR HANSEN COAL ZONE COAL

RESOURCES

A confidence interval is a statistic designed to capture uncertainty associated with

a point estimate. In this study we computed 90-percent confidence intervals on the

volume (total resource in millions of short tons) of coal in the Hansen coal zone in

the measured, indicated, inferred, and hypothetical categories.

The three main potential sources of error that might bias the confidence intervals

are preferential sampling, measurement errors, and model fitting. The probabilistic

interpretation of a confidence interval is based upon a random sample, which does

not occur in this situation, as there is preferential sampling in those areas deemed

to be minable. Measurement error can be caused by an error in recording the coal

bed thickness or in the definition of coverage areas. Modeling fitting variability

and bias result from the choice of models and fitting procedures.

Confidence limits for coal resources of the Hansen coal zone in the BowmanDickinson coalfield were calculated by J.H. Schuenemeyer and H.C. Power. The

data set that they used contained net coal measurements from 258 locations. This

data only included locations that contained Hansen coal (no 0 net coal thickness

values) and data that were representative of the entire coal zone (no terminated

holes).
WN-10

The confidence limits were derived through a complex series of steps. These steps

included investigating coal thickness trends (no significant trend was detected),

using coal thickness to compute a semivariagram, and fitting the semivariagram to

a spherical model. Parameter estimates were sill=12.14 ft2, nugget=3.96 ft2, and

range=6.63 miles. Standard deviations of coal thickness were obtained from the

semivariogram model. Differences in point densities were compensated for by

calculating sample size, called a pseudo n, within each reliability category and

calculating the variability of volume for each of the reliability categories.

Volumes of Hansen coal were then calculated at a 90-percent confidence interval

with measurement error. Some of the parameters used and results of the confidence

interval calculations are shown in tables WN-11 and WN-12. A detailed

description of the methodology used is given in Schuenemeyer and Power (in

press) and in Ellis and others (1999 and in press).
WN-11

COAL RESOURCES—BEULAH-ZAP COAL ZONE, BEULAH

COALFIELD, WILLISTON BASIN, NORTH DAKOTA

BEULAH-ZAP COAL ZONE RESOURCE ESTIMATES—AN

OVERVIEW

• Coal resources are calculated using the specific gravity of the coal calculated

from apparent coal rank, which is the weight of coal per unit volume, net coal

thickness, and areal extent of the coal.

• Resource tables for the Beulah-Zap coal zone in the Beulah coalfield include

coal and overburden thickness categories from Wood and others (1983), which

are based on apparent coal rank. Resources are also reported by county, Federal

coal and surface ownership categories, and 7.5-minute quadrangle.

• Following USGS published guidelines (Wood and others, 1983); coal resource

estimates are divided into measured, indicated, and inferred categories

according to relative abundance and reliability of data.

• Where data are widely spaced a hypothetical resource may be extrapolated.

• Measured resources are tonnage estimates of coal in the coal zone within a

radius of 0.25 mi of a control point where the net thickness of coal is measured.

• Indicated resources are tonnage estimates of coal that is within a radius of 0.25-

0.75 mi of a control point where the net thickness of the coal is measured.

• Inferred resources are tonnage estimates of coal that is within a radius of 0.75-3

mi of a control point where the net thickness of the coal is measured.
WN-12

• Hypothetical resources are tonnage estimates of coal that is beyond a radius of 3

mi of a control point where the net thickness of coal is measured.

• These resource categories assume a high to low degree of geologic certainty. A

statistical method that measures levels of uncertainty (confidence limits) for the

Beulah-Zap resource estimates in the Beulah coalfield is also included in this

study.

• Resource estimates are reported in millions of short tons with two significant

figures.

Beulah-Zap Coal Zone Coal Resources

The lateral extent (study limit) of the Beulah-Zap coal zone is defined by outcrop

information from Groenwald and others (1979), erosional “want” areas interpreted

from our stratigraphic data, and a generalized western boundary on the two largest

western pods of data based on our data limits. The entire study area is about

297,000 acres (120,192 hectares) in size.

Beulah-Zap coal resources in the Beulah coalfield, in the Williston Basin of North

Dakota were calculated using several software packages and custom programs.

Details of the resource calculation methodology are given in Ellis and others

(1999, in press).

To calculate the Beulah-Zap coal resources data was compiled in a StratiFact*

(GRG Corporation, 1996) relational database. The coal beds that made up the

Beulah-Zap coal zone were then correlated in the database. A custom program was

used to calculate net coal thickness at each data point (drill hole or measured

section) location.
WN-13

The net coal thickness and overburden were gridded, and isopach maps were

produced using EarthVision* (Dynamic Graphics, Inc., 1997) software. The grids

were made using an isopach grid option (special handling of 0 values and

terminated data) with a grid spacing of 150 x 150 meters.

The spatial parameters for querying the coal resources (for example, 7.5-minute

quadrangle (fig. WN-9) map area (U.S. Geological Survey National Mapping

Division, unpublished data, undated), Federal coal and surface ownership (fig.

WN-10) (Office of Surface Mining, unpublished data, undated), and reliability,

coal thickness (fig. WN-11), and overburden (fig. WN-12) categories) were created

on individual layers as ARC/INFO* (ESRI, 1998a) polygon coverages. The

coverages were unioned to make one polygon coverage with many attributes for

each polygon. The polygons in the union coverage were edited in ARC/INFO* and

ArcView* (ESRI, 1998b).

Coal resources were calculated using the EarthVision* (EV) volumetrics tool,

which calculates tonnages in each polygon in the union coverage using the net coal

thickness grid, the area of each polygon, and a conversion factor of 1,750 short

tons per acre-ft for lignite rank coal (Wood and others, 1983). Data from the EV

volumetrics report and the union coverage polygon attribute table were combined

in Excel* (Microsoft, 1997) spreadsheet software. Data for polygons containing

Beulah-Zap mine areas (fig. WN-11) or areas of net coal less than 2.5 ft in

thickness were deleted from the data set. Resource tables were created using data

from the remaining polygons (tables WN-13, WN-14, and WN-15). The final

resource area (fig. WN-11) (area that met all coal resource criteria) was about

257,000 acres (104,004 hectares) in size.

*Commercial software package
WN-14

CONFIDENCE LIMITS FOR BEULAH-ZAP COAL ZONE COAL

RESOURCES

A confidence interval is a statistic designed to capture uncertainty associated with

a point estimate. In this study we computed 90-percent confidence intervals on the

volume (total resource in millions of short tons) of coal in the Beulah-Zap coal

zone in the measured, indicated, inferred, and hypothetical categories.

The three main potential sources of error that might bias the confidence intervals

are preferential sampling, measurement errors, and model fitting. The probabilistic

interpretation of a confidence interval is based upon a random sample, which does

not apply in this situation, because there is preferential sampling in those areas

deemed to be minable. Measurement error can be caused by an error in recording

the coal bed thickness or in the definition of coverage areas. Modeling fitting

variability and bias result from the choice of models and fitting procedures.

Confidence limits for coal resources of the Beulah-Zap coal zone in the Beulah

coalfield, Williston Basin, North Dakota were calculated by J.H. Schuenemeyer

and H.C. Power. The data set that they used contained net coal measurements from

2,040 locations. This data set only included locations that contained Beulah-Zap

coal (no 0 net coal thickness values) and data that were representative of the entire

coal zone (no terminated holes).

The confidence limits were derived through a complex series of steps. These steps

included modeling coal thickness trends and removing the coal thickness trends

using a nonparametric regression algorithm called loess (with span=0.5). Spatial

correlation, as determined from the semivariogram of residual thickness, was

negligible. Standard deviations of coal thickness were obtained from the residual
WN-15

thickness. Differences in point densities were compensated for by calculating

sample size, called a pseudo n, within each reliability category and calculating the

variability of volume for each of the reliability categories. Volumes of Beulah-Zap

coal were then calculated at a 90-percent confidence interval with measurement

error. Some of the parameters used and results of the confidence interval

calculations are shown in tables WN-16 and WN-17. A detailed description of the

methodology used is given in Schuenemeyer and Power (in press) and in Ellis and

others (1999, in press).
WN-16

COAL RESOURCES—HAGEL COAL ZONE, BOWMANDICKINSON COALFIELD, WILLISTON BASIN, NORTH

DAKOTA

HAGEL COAL ZONE RESOURCE ESTIMATES—AN OVERVIEW

• Coal resources are calculated using the specific gravity of the coal calculated

from apparent coal rank, which is the weight of coal per unit volume, net coal

thickness, and areal extent of the coal.

• Resource tables for the Hagel coal zone in the Center-Falkirk coalfield include

coal and overburden thickness categories from Wood and others (1983), which

are based on apparent coal rank. Resources are also reported by county, Federal

coal and surface ownership categories, and 7.5-minute quadrangle.

• Following USGS published guidelines (Wood and others, 1983); coal resource

estimates are divided into measured, indicated, and inferred categories

according to relative abundance and reliability of data.

• Where data are widely spaced a hypothetical resource may be extrapolated.

• Measured resources are tonnage estimates of coal in the coal zone within a

radius of 0.25 mi of a control point where the net thickness of coal is measured.

• Indicated resources are tonnage estimates of coal that is within a radius of 0.25-

0.75 mi of a control point where the net thickness of the coal is measured.

• Inferred resources are tonnage estimates of coal that is within a radius of 0.75-3

mi of a control point where the net thickness of the coal is measured.
WN-17

• Hypothetical resources are tonnage estimates of coal that is beyond a radius of 3

mi of a control point where the net thickness of coal is measured.

• These resource categories assume a high to low degree of geologic assurance.

A statistical method that measures levels of uncertainty (confidence limits) for

the Hagel resource estimates in the Center-Falkirk coalfield is also included in

this study.

• Resource estimates are reported in millions of short tons with two significant

figures.

HAGEL COAL ZONE COAL RESOURCES

The lateral extent (study limit) of the Hagel coal is defined by outcrop information

from the Groenwald and others (1979), erosional “want” areas interpreted from our

stratigraphic data, and a generalized western boundary on the two largest western

pods of data based on our data limits. The entire study area is 336,000 acres

(135,975 hectares) in size.

Hagel coal resources in the Center-Falkirk coalfield, in the Williston Basin of

North Dakota were calculated using several software packages and custom

programs. Details of the resource calculation methodology are given in Ellis and

others (1999, in press).

To calculate the Hagel coal resources data was compiled in a StratiFact* (GRG

Corporation, 1996) relational database. Coal beds that made up the Hagel coal

zone were then correlated in the database. A custom program was used to
WN-18

calculate net coal thickness at each data point (drill hole or measured section)

location.

The net coal thickness and overburden were gridded, and isopach maps were

produced using EarthVision* (Dynamic Graphics, Inc., 1997) software. The grids

were made using an isopach grid option (special handling of 0 values and

terminated data) with a grid spacing of 150 x 150 meters.

The spatial parameters for querying the coal resources (for example, 7.5-minute

quadrangle (fig. WN-13) map area (U.S. Geological Survey National Mapping

Division, unpublished data, undated), Federal coal and surface ownership (fig.

WN-14) (Office of Surface Mining, unpublished data, undated), and reliability, net

coal thickness (fig. WN-15), and overburden (fig. WN-16) categories) were created

on individual layers as ARC/INFO* (ESRI, 1998a) polygon coverages. The

coverages were unioned to make one polygon coverage with many attributes for

each polygon. The polygons in the union coverage were edited in ARC/INFO* and

ArcView* (ESRI, 1998b).

Coal resources were calculated using the EarthVision* (EV) volumetrics tool,

which calculates tonnages in each polygon in the union coverage using the net coal

thickness grid, the area of each polygon, and a conversion factor of 1,750 short

tons per acre-ft for lignite rank coal (Wood and others, 1983). Data from the EV

volumetrics report and the union coverage polygon attribute table were combined

in Excel* (Microsoft, 1997) spreadsheet software. Data for polygons containing

Hagel mine areas (fig. WN-15) or areas of net coal less than 2.5 ft in thickness

were deleted from the data set. Resource tables were created using data from the

remaining polygons (tables WN-18, WN-19, and WN-20). The final resource area
WN-19

(fig. WN-15) (area that met all coal resource criteria) was about 256,000 acres

(103,600 hectares) in size.

*Commercial software package

CONFIDENCE LIMITS FOR HAGEL COAL ZONE COAL RESOURCES

A confidence interval is a statistic designed to capture uncertainty associated with

a point estimate. In this study we computed 90-percent confidence intervals on the

volume (total resource in millions of short tons) of coal in the Hagel coal zone in

the measured, indicated, inferred, and hypothetical categories.

The three main potential sources of error that might bias the confidence intervals

are preferential sampling, measurement errors, and model fitting. The probabilistic

interpretation of a confidence interval is based upon a random sample, which does

not apply in this situation, because there is preferential sampling in those areas

deemed to be minable. Measurement error can be caused by an error in recording

the coal bed thickness or in the definition of coverage areas. Modeling fitting

variability and bias result from the choice of models and fitting procedures.

Confidence limits for coal resources of the Hagel coal zone in the Center-Falkirk

coalfield, Williston Basin, North Dakota were calculated by J.H. Schuenemeyer

and H.C. Power. The data set that they used contained net coal measurements from

1,672 locations. This data set only included locations that contained Hagel coal (no

0 net coal thickness values) and data that were representative of the entire coal

zone (no terminated holes).

The confidence limits were derived through a complex series of steps. These steps

included investigating coal thickness trends (no significant trend was detected),
WN-20

using coal thickness to compute a semivariagram, and fitting the semivariagram to

an exponential model. Parameter estimates were sill=31.99 ft2, nugget=13.73 ft2,

and range=4.71 miles. Standard deviations of coal thickness were obtained from

the semivariogram model. Differences in point densities were compensated for by

calculating sample size, called a pseudo n, within each reliability category and

calculating the variability of volume for each of the reliability categories.

Volumes of Hagel coal were then calculated at a 90-percent confidence interval

with measurement error. Some of the parameters used and results of the

confidence interval calculations are shown in tables WN-21 and WN-22. A

detailed description of the methodology used is given in Schuenemeyer and Power

(in press) and in Ellis and others (1999, in press).
WN-21

REFERENCES CITED

Cherven, V.B. and Jacob, A.R., 1985, Evolution of Paleogene depositional

systems, Williston Basin in response to global sea level changes, in R.M.

Flores and S.S. Kaplan eds., Cenozoic Paleogeography of the West-central

United States: Society of Economic Paleontologist and Mineralogists, Rocky

Mountain Rocky Mountain Paleogeography Symposium 3, p. 127-170, fig.

12.

Dynamic Graphics, Inc., 1997, EarthVision, v.4: Dynamic Graphics, Inc., 1015

Atlantic Ave., Alameda, CA 94501.

Ellis, M.S., Gunther, G.L., Flores, R.M., Ochs, A.M., Stricker, G.D., Roberts, S.B.,

Taber, T.T., Bader, L.R., and Schuenemeyer, J.H., 1999, Preliminary report

on coal resources of the Wyodak-Anderson coal zone, Powder River Basin,

Wyoming and Montana: U.S. Geological Survey Open-File Report 98-789A.

Ellis, M.S., Gunther, G.L., Flores, R.M. Stricker, G.D., and Ochs, A.M., in press,

Preliminary report on methodolgy for calculating coal resources of the

Wyodak-Anderson coal zone in the Powder River Basin, Wyoming and

Montana, U.S. Geological Survey Open-File Report 98-789B.

ESRI-Environmental Systems Research Institute, Inc., 1998a, ARC/INFO, v. 7.1.1:

Environmental Systems Research Institute, Inc., 380 New York Street,

Redlands, CA 92373, USA.

_____ 1998b, ArcView, v.3.0a: Environmental Systems Research Institute, Inc.,

380 New York Street, Redlands, CA 92373, USA.
WN-22

GRG Corporation, 1996, StratiFact, relational database software, v. 4.5: GRG

Corporation, 4175 Harlan Street, Wheatridge, CO 80033-5150, USA.

Groenwald, G.H., Hemish, L.A., Cherry, J.A., Rehm, B.W., Meyer, G.N., and

Winczewski, L.M., 1979, Geology and geohydrology of the Knife River

Basin and adjacent areas of west-central North Dakota: North Dakota

Geological Survey Report of Investigations 64, p. 402, scale 1:100,000.

Microsoft, 1997, Excel spreadsheet software, v. Office 97: Microsoft Corporation,

1 Microsoft Way, Redman, WA 98052.

Rehbein, E.A., 1977, Preliminary report on stratigraphy and depositional

environments of the lignites in the Fort Union Formation, west central North

Dakota: U.S. Geological Survey Open-File Report 77-69, 23 p.

Schuenemeyer, J. H. and Power H.C., in press, Uncertainty estimation for resource

assessment—An application to coal: Mathematical Geology.

Wood, G.H. Jr., Kehn, T.M., Carter, M.D., and Culbertson, W.C., 1983, Coal

resource classification system of the U.S. Geological Survey: U.S.

Geological Survey Circular 891, 65 p.
BOWMAN ADAMS

STARK

County line

BILLINGS

Harmon Study

 Limit

7

9 10 12 13

36 37 38 39 40 41 42 43 44 45 46 47 49 50

67 68 69 70 71 72 73 75 76 77 78 79 80 81

82 83 84 86 87 88 90 91 92 93 94 95 96

98 99 102 103 104 105 106 107

113 114 115 119 120 121 122 123

Figure WN-1. Location of 7.5-minute quadrangle maps in the Harmon study 

limit.

124 125

100 101

85

116 117 118

97

112

Miles

Kilometers

47

104 103 102

46

o

o

o o o

0 10 20 30 40

0 10 20 30 40 50 60

1 2

4 5

15 16 17 19 20 21

23 24 25 26 27 28 29 32 33

53 54 55 56 57 58 60 61 62 63 64 65 66

74

89

51 52

8 11

VALLEY

GOLDEN

14 18

22

34 35

30 31

HETTINGER

48

SLOPE

59

Williston Basin (part)

3 6

108 109 110 111
No Federal coal or surface

No Federal coal, but Federal 

surface

Federal coal, but no Federal 

surface

Federal coal = Federal Federal coal and surface

subsurface management of 

all minerals, coal only, 

or oil, gas, and coal 

Federal surface = Federal 

surface ownership

Williston Basin (part)

Figure WN-2. Federal coal and surface ownership in the Harmon study limit. 

Harmon Study

 Limit

0 10 20 30

50

Miles

0 10 20 30 40 Kilometers

104 103 102

47

46

o o o

o

o
ure WN-3. Harmon net coal isopach map and resource area. 

ADAMS BOWMAN

LOPE

STARK

BILLINGS

VALLEY

Harmon Study

 Limit

Miles

Kilometers

5

10

20

30

0 10 20 30

0 10 20 30 40 50

Index map showing area

included in resource calculations

(does not include areas of mines 

or net coal < 2.5 ft thick)

Mine

area

HETTINGER Williston Basin 

(part)

Resource area

County line
ADAMS BOWMAN

SLOPE

STARK

HETTINGER

County line

BILLINGS

VALLEY

Harmon Study

 Limit

gure WN-4. Harmon overburden isopach map.

100

200

300

400

500

1000

2000

Williston Basin 

(part)

Miles

Kilometers

0 10 20 30

0 10 20 30 40 50
Hansen Study

 Limit

ADAMS

BOWMAN

STARK

BILLINGS GOLDEN

VALLEY

HETTINGER

0 10 20 30 40

0 20 40 60

Miles

Kilometers

47

104 103 102

46

o o o

o

o

87 88 89 90 91 92 93

78 79 83 84 86

67 71 72

2

4 5

7 8 9 10

12 13 14 15 16

38

19 20 22 26

29 30 31 32 33 34 37

40 41 42 43 44 45 48 49 50 51

65 66 68 69 73 74 75 76 77

81 82

17

25

SLOPE

52 53 54 55 56 57 58 59 61 62 64

46

60 63

35

1

3

6

11

21

28

23 24

39

36

27

47

70

80 85

County line

Williston Basin 

(part)

18

Figure WN-5. Location of 7.5-minute quadrangle maps in the Hansen study 

limit.
0 10 20 30

50

Miles

0 10 20 30 40 Kilometers

104

47

46

o o o

o

o

103 102

Hansen Study

 Limit

No Federal coal or surface

No Federal coal, but Federal 

surface

Federal coal, but no Federal 

surface

Federal coal = Federal Federal coal and surface

subsurface management of 

all minerals, coal only, 

or oil, gas, and coal 

Federal surface = Federal 

surface ownership

Williston Basin (part)

Figure WN-6. Federal coal and surface ownership in the Hansen study limit. 
ADAMS

BOWMAN

LOPE

STARK

HETTINGER

BILLINGS

GO

VALLEY

Hansen Study

 Limit

Mine area

Index map showing area

included in resource calculations

(does not include areas of mines or 

net coal < 2.5 ft thick)

0 10 20 30 40

0 20 40 60

Miles

Kilometers

Williston Basin 

(part)

gure WN-7. Hansen net coal isopach map and resource area.

County line

2.5

5

10

20

Resource area
ADAMS

BOWMAN

LOPE

STARK

HETTINGER

BILLINGS

GOLDEN

VALLEY

Hansen Study

 Limit

0 10 20 30 40

0 20 40 60

Miles

Kilometers

100

200

300

400

500

1000

County line

Williston Basin 

(part)

gure WN-8. Hansen overburden isopach map.
101 30' o

Figure WN-9. Location of 7.5-minute quadrangle maps in the Beulah-Zap 

study limit.

Miles

Kilometers

0 10 20

0 10 20 30 40

 1 Roseglen

 2 Blue Hill

 3 Douglas West

 4 Douglas East

 5 Blackwater Lake

 6 Emmett

 7 Emmett NE

 8 Garrison

 9 Emmett SE

10 Garrison Dam North

11 Golden Valley NE

12 Beulah NW

13 Beulah NE

14 Hazen NW

15 Hazen NE

16 Golden Valley

17 Zap

18 Beulah

19 Hazen West

20 Hazen East

21 Schaffner Creek NE

22 Medicine Butte

23 Medicine Butte NE

24 Red Butte NW

25 Red Butte 

26 Hannover NW

27 Willow Creek East

28 Medicine Butte SW

29 Medicine Butte SE

30 Red Butte SW

31 Otter Creek

32 Glen Ullin NW

33 Glen Ullin NE

34 Hailstone Butte

Key to 7.5-minute 

quadrangle maps

47 

47 30'

102 

o

o

o

5 15

3 4

5 6 7

9

20

24 26

10

32

31

33 34

8

18

30

Williston

Basin

(part)

21

28

22

16 17 19

11 12 13 14 15

25

1 2

23

27 29
o o

Figure WN-10. Federal coal and surface ownership in the Beulah-Zap 

study limit.

County line

Williston Basin (part)

No Federal coal or surface

Federal coal = Federal subsurface Federal coal, but no Federal surface

management of all minerals, coal 

only, or oil, gas, and coal 

Federal surface = Federal surface 

ownership

MERCER

OLIVER

MORTON

McLEAN

47 

47 30'

102 101 30'

o

o

Miles

Kilometers

0 10

0 10

5
2.5

5

10

20

30

40

50

0

Miles

Kilometers

0 8 12

0 5 10 15 20

4

Beulah-Zap study limit

Resource area

Index map showing area

included in resource 

calculations

(does not include areas of mines, 

clinker, or net coal < 2.5 ft thick)

Mine 

areas

Mercer

Oliver

Morton

McLean

Net coal thickness 

(ft)

Figure WN-11. Beulah-Zap net coal isopach map and resource area. 

102 

47 30'

47 

101 30'

o

o o

o

County line

Williston Basin 

(part)
Overburden 

thickness 

(ft)

Miles

Kilometers

0 4 8 12 16 20

0 10 20 30

0

50

100

200

300

MERCER

OLIVER

MORTON

McLEAN

47 

47 30'

102 101 30'

o

o o

o

Figure WN-12. Beulah-Zap overburden isopach map. 

Beulah-Zap 

study limit

County line

Williston Basin 

(part)
Figure WN-13. Location of 7.5-minute quadrangle maps in the Hagel study 

limit.

Miles

Kilometers

101 30 101

47 30

47

0 10 20

0 10 20 30 40

o

o

o o

5 15

11 Washburn NE

12 Turtle Creek NW

13 Beulah

14 Hazen West

15 Hazen East

16 Stanton

17 Stanton SE

18 Washburn SW

19 Washburn

20 Red Butte NW 

1 2 3 4

1 Emmett SW

2 Riverdale North

3 Coleharbor

4 Lake Nettie

5 Beulah NE

6 Hazen NW	

7 Hazen NE

8 Garrison Dam South

9 Riverdale South

10 Underwood

21 Red Butte

22 Hannover NW

23 Hannover NE

24 Fort Clark

25 Red Butte

26 Otter Creek

27 Hannover

28 Center

29 Nelson Lake

Key to 7.5-minute quadrangle maps

23

26 28

14

5 6 7 8 9 10 11 12

13 15 16 17 18 19

21 22

25 29

20 24

27

Williston 

Basin

(part)
101 30 101

47 30

47o

o

o o

Figure WN-14. Federal coal and surface ownership in the Hagel study limit

Center-Falkirk coalfield.

No Federal coal or surface

Federal coal, but no Federal 

surface

Federal coal = Federal subsurface 

management of all minerals, coal only, 

or oil, gas, and coal 

Federal surface = Federal surface 

ownership

Miles

Kilometers

0 10 20

0 10 20 30 40

Williston Basin (part)

5 15

McLEAN

MERCER

OLIVER
2.5

5

10

20

30

40

0

10 20

10 20 30

Miles

Kilometers

gure WN-15. Hagel net coal isopach map and resource area. 

County line

5 15

Mercer Oliver

Burleigh

Hagel study limit

Mine 

 areas

Mine 

areas

Resource area

Index map showing area

included in resource calculations

(does not include areas of mines 

or net coal < 2.5 ft thick)

Williston

Basin

(part)
gure WN-16. Hagel overburden isopach map. 

Overburden thickness 

(ft)

0

50

100

200

300

400

MERCER OLIVER

County line

Hagel study limit

0 10 20

0 10 20 30

Miles

Kilometers

5 15

Williston Basin (part)
Table WN-1. Coal resources of the Harmon coal zone in the Bowman-Dickinson coalfield, Williston Basin, North

Dakota, reported by county (fig. WN-1), overburden (fig. WN-4), coal thickness (fig. WN-3), and reliability

categories. Zeros (0) indicate areas where no resources were calculated. Table does not include resources for coal

less than 2.5 ft thick or coal in mine areas (fig. WN-3). Resources are reported in millions of short tons (MST) with

two significant figures. Resource numbers will not sum to match totals due to independent rounding

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

ADAMS 0-100 ft 2.5-5 ft 3.7 20 160 110 290

5-10 ft 18 120 1,000 690 1,800

10-20 ft 5.5 39 250 64 360

0-100 ft total 27 180 1,400 860 2,500

100-200 ft 2.5-5 ft 3.4 18 110 16 140

5-10 ft 10 52 260 22 340

10-20 ft 1.8 18 43 0 63

100-200 ft total 16 89 410 39 550

200-500 ft 2.5-5 ft 10 22 25 0 57

5-10 ft 19 62 51 0 130

10-20 ft 39 120 68 0 220

20-40 ft 0.20 0 0 0 0.20

200-500 ft total 68 200 140 0 410

ADAMS total 110 470 2,000 900 3,400

BILLINGS 0-100 ft 2.5-5 ft 0 0 0.18 0 0.18

5-10 ft 2.0 10 88 0 100

10-20 ft 0 6.1 58 0 64

0-100 ft total 2.0 16 150 0 160

100-200 ft 2.5-5 ft 0.81 2.1 4.2 9.0 16

5-10 ft 0 5.3 94 3.8 100

10-20 ft 4.4 38 92 0 130

20-40 ft 0 5.5 11 0 16

100-200 ft total 5.3 51 200 13 270
Table WN-1. Harmon coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

BILLINGS 200-500 ft 2.5-5 ft 0.072 0.84 36 36 73

5-10 ft 0.23 2.5 87 69 160

10-20 ft 9.7 52 190 0 250

20-40 ft 0.93 5.7 110 0 110

200-500 ft total 11 61 420 110 600

>500 ft 2.5-5 ft 0 0 31 200 230

5-10 ft 4.0 22 330 470 830

10-20 ft 8.8 58 280 44 390

20-40 ft 0 0 20 0 20

>500 ft total 13 79 660 720 1,500

BILLINGS total 31 210 1,400 830 2,500

BOWMAN 0-100 ft 2.5-5 ft 3.3 19 71 73 170

5-10 ft 9.3 53 210 56 320

10-20 ft 13 63 440 63 580

20-40 ft 40 220 420 64 740

0-100 ft total 66 360 1,100 260 1,800

100-200 ft 2.5-5 ft 16 42 24 0.10 83

5-10 ft 24 53 56 0 130

10-20 ft 37 160 150 0 350

20-40 ft 20 97 21 0 140

100-200 ft total 97 350 250 0.10 700

200-500 ft 2.5-5 ft 8.2 15 6.0 0 29

5-10 ft 55 120 59 0 230

10-20 ft 11 30 33 0 74

200-500 ft total 74 160 98 0 330

BOWMAN total 240 870 1,500 260 2,800
Table WN-1. Harmon coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

GOLDEN 0-100 ft 2.5-5 ft 3.4 27 120 93 240

VALLEY 5-10 ft 10 59 160 13 240

10-20 ft 17 74 39 0 130

20-40 ft 5.0 16 6.9 0 27

0-100 ft total 35 170 320 110 640

100-200 ft 2.5-5 ft 0.51 3.3 60 48 110

5-10 ft 2.5 20 170 48 240

10-20 ft 31 190 230 0 450

20-40 ft 31 210 330 22 590

100-200 ft total 65 420 780 120 1,400

200-500 ft 2.5-5 ft 0 0 42 120 160

5-10 ft 3.3 21 270 350 640

10-20 ft 5.5 63 310 190 570

20-40 ft 11 61 460 0 540

200-500 ft total 20 150 1,100 660 1,900

>500 ft 2.5-5 ft 0 0.14 15 180 190

5-10 ft 2.7 19 220 1,200 1400

10-20 ft 0 0 180 1,400 1,600

20-40 ft 0 0 22 2.5 24

>500 ft total 2.7 19 440 2,800 3,300

GOLDEN VALLEY total 120 760 2,600 3,700 7,200

HETTINGER 0-100 ft 2.5-5 ft 0 0 0 8.4 8.4

5-10 ft 0 0 1.6 220 230

10-20 ft 0 2.8 38 72 110

0-100 ft total 0 2.8 40 310 350
Table WN-1. Harmon coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

HETTINGER 100-200 ft 2.5-5 ft 0.9 4.7 37 57 99

5-10 ft 2.9 33 240 770 1,000

10-20 ft 0 0 240 1,200 1,400

20-40 ft 0 6.4 130 18 150

100-200 ft total 3.8 44 640 2,000 2,700

200-500 ft 2.5-5 ft 1.3 8.1 68 240 310

5-10 ft 1.5 9.2 250 1,900 2100

10-20 ft 9.4 75 1,300 2,900 4,300

20-40 ft 12 89 800 570 1,500

200-500 ft total 25 180 2,500 5,500 8,200

>500 ft 5-10 ft 0 0 0 450 450

10-20 ft 0 0 0 780 780

>500 ft total 0 0 0 1,200 1,200

HETTINGER total 28 230 3,100 9,100 13,000

SLOPE 0-100 ft 2.5-5 ft 3.7 16 180 40 240

5-10 ft 47 240 890 130 1,300

10-20 ft 27 160 1200 700 2,100

20-40 ft 54 360 430 110 940

0-100 ft total 130 770 2,700 980 4,500

100-200 ft 2.5-5 ft 0.33 2.1 5.3 4.6 12

5-10 ft 6.7 40 73 15 130

10-20 ft 27 190 550 7.3 770

20-40 ft 63 350 280 0 700

100-200 ft total 97 580 910 27 1,600

200-500 ft 2.5-5 ft 0.91 5.7 74 12 92

5-10 ft 8.2 64 850 250 1,200

10-20 ft 32 280 2,500 410 3,300
Table WN-1. Harmon coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

SLOPE 200-500 ft 20-40 ft 16 160 1,100 3.9 1,300

200-500 ft total 57 500 4,600 670 5,800

>500 ft 2.5-5 ft 0 0 1.7 0 1.7

5-10 ft 0.73 6.9 86 37 130

10-20 ft 24 150 660 7.7 830

20-40 ft 1.3 8.3 15 0 25

>500 ft total 26 160 760 44 990

SLOPE total 310 2,000 8,900 1,700 13,000

STARK 0-100 ft 10-20 ft 0 0 0 0.083 0.083

0-100 ft total 0 0 0 0.083 0.083

200-500 ft 2.5-5 ft 0 0 0 64 64

5-10 ft 0 0 0 9.6 9.6

200-500 ft total 0 0 0 73 73

>500 ft 2.5-5 ft 0 0 0 270 270

5-10 ft 0 0 28 1,600 1,600

10-20 ft 3.2 42 610 580 1,200

>500 ft total 3.2 42 640 2,400 3100

STARK total 3.2 42 640 2,500 3,200

Grand total (MST) 850 4,600 20,000 19,000 45,000
Table WN-2. Coal resources of the Harmon coal zone in the Bowman-Dickinson coalfield, Williston Basin, North

Dakota, reported by 7.5-minute quadrangle map area (see quadrangle location map (fig. WN-1) and key (table

WN-4)). Resources are reported in millions of short tons (MST) with two significant figures. The table does not

include resources for areas containing net coal less than 2.5 ft thick, or coal in mine or lease areas (fig. WN-3).

Resource numbers will not sum to match total due to independent rounding

7.5-minute quadrangle map Index map

number

Total (MST) 7.5-minute quadrangle map Index map

number

Total (MST)

ABBEY HILL 92 340 CHIMNEY BUTTE 26 450

ALPHA 36 180 CLARK BUTTE 66 160

AMIDON 71 1,100 CLARK BUTTE NE 50 0

AMIDON SE 86 620 CLARK BUTTE NW 49 0.74

BARTHS BUTTE 121 10 CLARK BUTTE SW 65 300

BEACH EAST 15 1,000 CLIFFS PLATEAU 39 210

BEACH WEST 14 470 COFFIN BUTTES 112 7.2

BELFIELD 21 0 DAGLUM 42 670

BELFIELD SE 30 72 DAGLUM NW 41 730

BELFIELD SW 29 240 DAGLUM SE 58 810

BENTLEY 96 520 DAGLUM SW 57 920

BLACK BUTTE 70 1,100 DEEP CREEK NORTH 54 560

BOWMAN 100 400 DEEP CREEK SOUTH 69 400

BOWMAN SE 113 9.4 DICKINSON SOUTH 32 15

BOYCE CREEK EAST 68 430 DRY BULLION CREEK 37 360

BOYCE CREEK WEST 67 100 DUCK CREEK 22 300

BUCYRUS 117 4.2 EAST RAINY BUTTE 74 250

BUFFALO GAP CAMPGROUND 17 330 EHLER LAKE 106 340

BULLION BUTTE 38 780 ENTERPRISE SCHOOL 90 110

BURT 95 610 FRYBURG 28 170

BURT NW 80 510 FRYBURG NE 20 0

CARLYLE 34 70 FRYBURG NW 19 4.4

CEDAR BUTTE 122 13 GASCOYNE 115 220

CEDAR LAKE 89 400 GOLVA 35 110
Table WN-2. Harmon coal resources—continued

7.5-minute quadrangle map Index map

number

Total (MST) 7.5-minute quadrangle map Index map

number

Total (MST)

GORHAM SW 13 0 NEW LEIPZIG SOUTH 97 3.8

GRIFFIN 99 29 NORTH STAR BUTTE 81 350

HAVELOCK 76 1,100 ODLAND DAM 8 180

HAYNES 125 3.9 ODLAND DAM NE 3 30

HETTINGER NORTH 118 160 OLLIE 51 0

HOOTOWL CREEK EAST 5 220 PEARL BUTTE 120 150

HOOTOWL CREEK SW 9 700 PEARL BUTTE NW 108 220

HOOTOWL CREEK WEST 4 280 PLUM BUTTE 110 400

IVES 83 640 PLUM BUTTE NE 111 510

JUNG LAKE 75 690 REEDER 116 210

JUNIPER SPUR 55 650 REGENT 77 1,200

KID RICH BUTTE 124 33 RHAME 98 97

LEFOR 46 210 ROCKY RIDGE NORTH 40 410

LEFOR SW 61 670 ROCKY RIDGE SOUTH 56 750

LEFOR NW 45 320 ROOSEVELT CREEK EAST 7 0

LEHIGH 33 0 ROOSEVELT CREEK WEST 6 46

LIENS DAMS 91 360 ODLAND DAM 8 180

LONG BUTTE 109 410 ODLAND DAM NE 3 30

MARMARTH SE 82 0.74 OLLIE 51 0

MEDORA 18 120 PEARL BUTTE 120 150

MINERAL SPRINGS 87 580 PEARL BUTTE NW 108 220

MOTT NORTH 79 560 PLUM BUTTE 110 400

MOTT NW 78 900 PLUM BUTTE NE 111 510

MOTT SOUTH 94 400 REEDER 116 210

MOTT SW 93 190 REGENT 77 1,200

NASON HILL 123 9 RHAME 98 97

NEW ENGLAND 60 660 ROCKY RIDGE NORTH 40 410

NEW ENGLAND NW 43 540 ROCKY RIDGE SOUTH 56 750

NEW ENGLAND SW 59 580 ROOSEVELT CREEK EAST 7 0
Table WN-2. Harmon coal resources—continued

7.5-minute Quadrangle map Index map

number

Total (MST) 7.5-minute Quadrangle map Index map

number

Total (MST)

ROOSEVELT CREEK WEST 6.0 46 THREE V CROSSING 52 150

SCHEFIELD 44 460 TRACY MOUNTAIN 27 47

SCRANTON 102 330 TROTTERS 2.0 8.7

SCRANTON NE 103 440 WANNAGAN CREEK EAST 12 170

SCRANTON SW 114 180 WANNAGAN CREEK WEST 11 490

SENTINEL BUTTE 16 580 WARNKE HILL 88 440

SENTINEL BUTTE SE 24 310 WEST FORK DEEP CREEK 84 750

SKAAR 1.0 13 WEST RAINY BUTTE 73 640

SOUTH HEART 31 71 WEST TWIN BUTTE 10 690

SPRING CREEK 53 560 WHETSTONE BUTTES 104 410

SQUARE BUTTE 25 330 WHITE BUTTE EAST 64 390

STEWART LAKE 85 1,200 WHITE BUTTE NE 48 54

STONY BUTTE 62 770 WHITE BUTTE NW 47 140

TALBOT BUTTE 101 200 WHITE BUTTE WEST 63 660

TAYLOR BUTTE 107 320 WHITE LAKE 72 700

TAYLOR BUTTE SE 119 480 WOLF BUTTE 105 140

THELAN 23 520 Grand total (MST) 45,000
Table WN-3. Harmon coal resources in the Bowman-Dickinson coalfield, North Dakota, reported by Federal coal

and surface ownership (fig. WN-2). Resources are shown in millions of short tons (MST) with 2 significant

figures. The table does not include resources in mine areas or in areas containing less than 2.5 ft of coal (fig. WN3). Resource numbers will not sum to match total due to independent rounding

Federal ownership Total (MST)

No Federal coal or surface ownership 27,000

No Federal coal, but Federal surface ownership 790

Federal coal, but no Federal surface ownership 15,000

Federal coal and surface ownership 2,200

Grand total (MST) 45,000
Table WN-4. Key to 7.5-minute quadrangle maps in the Harmon study limit (see figure WN-1 and table 2)

Number 7.5-minute quadrangle map Number 7.5-minute quadrangle

map

Number 7.5-minute quadrangle

map

1 SKAAR 27 TRACY MOUNTAIN 53 SPRING CREEK

2 TROTTERS 28 FRYBURG 54 DEEP CREEK NORTH

3 ODLAND DAM NE 29 BELFIELD SW 55 JUNIPER SPUR

4 HOOTOWL CREEK WEST 30 BELFIELD SE 56 ROCKY RIDGE SOUTH

5 HOOTOWL CREEK EAST 31 SOUTH HEART 57 DAGLUM SW

6 ROOSEVELT CREEK WEST 32 DICKINSON SOUTH 58 DAGLUM SE

7 ROOSEVELT CREEK EAST 33 LEHIGH 59 NEW ENGLAND SW

8 ODLND DAM 34 CARLYLE 60 NEW ENGLAND

9 HOOTOWL CREEK SW 35 GOLVA 61 LEFOR SW

10 WEST TWIN BUTTE 36 ALPHA 62 STONY BUTTE

11 WANNAGAN CREEK WEST 37 DRY BULLION CREEK 63 WHITE BUTTE WEST

12 WANNAGAN CREEK EAST 38 BULLION BUTTE 64 WHITE BUTTE EAST

13 GORHAM SW 39 CLIFFS PLATEAU 65 CLARK BUTTE SW

14 BEACH WEST 40 ROCKY RIDGE NORTH 66 CLARK BUTTE

15 BEACH EAST 41 DAGLUM NW 67 BOYCE CREEK WEST

16 SENTINEL BUTTE 42 DAGLUM 68 BOYCE CREEK EAST

17 BUFFALO GAP

CAMPGROUND

43 NEW ENGLAND NW 69 DEEP CREEK SOUTH

18 MEDORA 44 SCHEFIELD 70 BLACK BUTTE

19 FRYBURG NW 45 LEFOR NW 71 AMIDON

20 FRYBURG NE 46 LEFOR 72 WHITE LAKE

21 BELFIELD 47 WHITE BUTTE NW 73 WEST RAINY BUTTE

22 DUCK CREEK 48 WHITE BUTTE NE 74 EAST RAINY BUTTE

23 THELAN 49 CLARK BUTTE NW 75 JUNG LAKE

24 SENTINEL BUTTE SE 50 CLARK BUTTE NE 76 HAVELOCK

25 SQUARE BUTTE 51 OLLIE 77 REGENT

26 CHIMNEY BUTTE 52 THREE V CROSSING 78 MOTT NW
Table WN-4. Key to 7.5-minute quadrangle maps, Harmon study limit—continued

Number 7.5-minute quadrangle map Number 7.5-minute quadrangle map

79 NOTT NORTH 103 SCRANTON NE

80 BURT NW 104 WHETSTONE BUTTES

81 NORTH STAR BUTTE 105 WOLF BUTTE

82 MARMARTH SE 106 EHLAER LAKE

83 IVES 107 TAYLOR BUTTE

84 WEST FORK DEEP CREEK 108 PEARL BUTTE NW

85 STEWART LAKE 109 LONG BUTTE

86 AMIDON SE 110 PLUM BUTTE

87 MINERAL SPRINGS 111 PLUM BUTTE NE

88 WARNKE HILL 112 COFFIN BUTTES

89 CEDAR LAKE 113 BOWMAN SE

90 ENTERPRISE SCHOOL 114 SCRANTON SW

91 LIENS DAMS 115 GASCOYNE

92 ABBEY HILL 116 REEDER

93 MOTT SW 117 BUCYRUS

94 MOTT SOUTH 118 HETTINGER NORTH

95 BURT 119 TAYLOR BUTTE SE

96 BENTLEY 120 PEARL BUTTE

97 NEW LEIPZIG SOUTH 121 BARTHS BUTTE

98 RHAME 122 CEDAR BUTTE

99 GRIFFIN 123 NASON HILL

100 BOWMAN 124 KID RICH BUTTE

101 TALBOT BUTTE 125 HAYNES

102 SCRANTON
Table WN-5. Data used for computation of confidence intervals within reliability categories for Harmon coal

resources in the Bowman-Dickinson coalfield, Williston Basin, North Dakota. Volume refers to the calculated

resource in millions of short tons (MST). NA, not applicable

Parameter Reliability category Entire

Measured Indicated Inferred Hypothetical area

Area (in square meters) 177,067,168 868,859,831 4,352,969,100 5,065,252,495 10,464,148,594

Percent of area 2 8 42 48 100

Acres (area x 0.0002471) 43,754 214,700 1,075,642 1,251,651 2,585,747

SD (standard deviation (in ft) from

semivariogram model)

2.174 2.59 3.727 5.507 NA

Acre feet (acres x SD) 95,125 556,065 4,008,751 6,892,834 NA

Volume standard deviation (MST) 9 71 920 12,200 13,201

Pseudo n 348 190 59 1 NA

Table WN-6. Estimates of uncertainty (calculated with measurement error) for Harmon coal resources in the

Bowman-Dickinson coalfield, Williston Basin, North Dakota. To show detail, resources are reported in millions of

short tons (MST) with four significant figures

Parameter Reliability category Entire

Measured Indicated Inferred Hypothetical area

Total calculated resource (MST) 847.0 4,596 20,230 19,000 44,670

Lower 90% confidence limit (MST) 832.0 4,479 18,720 0.0 22,960

Upper 90% confidence limit (MST) 862.0 4,714 21,750 39,070 66,390
Table WN-7. Coal resources of the Hansen coal zone in the Bowman-Dickinson coalfield, Williston Basin, North

Dakota, reported by county (fig. WN-5), overburden (fig. WN-8), coal thickness (fig. WN-7), and reliability

categories. Zeros (0) indicate areas where no resources were calculated. The table does not include resources for

coal less than 2.5 ft thick or coal in mine areas (fig. WN-7). Resources are reported in millions of short tons (MST)

with two significant figures. Resource numbers will not sum to match totals due to independent rounding

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

ADAMS 0-100 ft 2.5-5 ft 0 0 19 1.0 20

5-10 ft 6.2 49 520 1,200 1,700

10-20 ft 6.2 48 470 200 730

0-100 ft total 12 98 1,000 1,400 2,500

100-200 ft 2.5-5 ft 0.083 3.9 16 5.7 25

5-10 ft 1.5 8.8 24 12 46

10-20 ft 1.1 0 0 0 1.1

100-200 ft total 2.7 13 40 18 73

200-500 ft 2.5-5 ft 5.7 33 110 10 160

5-10 ft 42 120 220 17 390

10-20 ft 31 16 0 0 46

200-500 ft total 79 170 320 27 600

>500 ft 5-10 ft 1.6 0.39 0 0 2.0

10-20 ft 2.2 0.42 0 0 2.6

>500 ft total 3.8 0.81 0 0 4.6

ADAMS total 97 280 1,400 1,400 3,200

BILLINGS 0-100 ft 2.5-5 ft 0 0.013 5.8 0.13 5.9

5-10 ft 0 0 6.4 6.5 13

10-20 ft 0.11 3.4 2.1 18 24

0-100 ft total 0.11 3.4 14 25 43

100-200 ft 2.5-5 ft 0 0 2.8 0 2.8

5-10 ft 0 0 0.74 0 0.74
Table WN-7. Hansen coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

BILLINGS 100-200 ft 10-20 ft 0 0 0 5.4 5.4

20-40 ft 0 0 0 21 21

100-200 ft total 0 0 3.5 27 30

200-500 ft 2.5-5 ft 0.89 4.0 38 6.1 49

5-10 ft 0 6.6 59 17 82

10-20 ft 3.1 11 110 160 280

20-40 ft 0 0 0 630 630

200-500 ft total 4 21 210 810 1,000

>500 ft 2.5-5 ft 0 0 6.3 35 41

5-10 ft 0 0 43 85 130

10-20 ft 6.2 24 110 330 470

20-40 ft 0 0 0 460 460

>500 ft total 6.2 24 160 910 1,100

BILLINGS total 10.0 48 390 1,800 2,200

BOWMAN 0-100 ft 2.5-5 ft 4.7 16 70 73 160

5-10 ft 8.7 42 240 270 560

10-20 ft 3.5 9.5 33 16 62

20-40 ft 0 0 0.24 0 0.24

0-100 ft total 17 67 340 360 790

100-200 ft 2.5-5 ft 4.2 13 14 2.2 33

5-10 ft 11 40 100 25 180

10-20 ft 0.83 2.8 8.2 0 12

20-40 ft 2.2 2.5 0 0 4.7

100-200 ft total 19 59 120 27 230
Table WN-7. Hansen coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

BOWMAN 200-500 ft 2.5-5 ft 28 60 33 0.13 120

5-10 ft 38 120 210 0.91 380

10-20 ft 10 79 190 0.86 280

20-40 ft 7.9 36 21 0 65

200-500 ft total 84 300 460 1.9 840

BOWMAN total 120 420 920 390 1,900

GOLDEN

VALLEY

0-100 ft 2.5-5 ft 0.88 6.6 12 2.4 22

5-10 ft 0 0.055 1.8 2.3 4.2

10-20 ft 0 0 0 5.6 5.6

0-100 ft total 0.88 6.7 14 10 32

100-200 ft 2.5-5 ft 0.079 2.6 14 0.75 18

5-10 ft 0.14 12 88 3.4 100

10-20 ft 0 1.5 11 32 44

20-40 ft 0 0 0 32 32

100-200 ft total 0.22 16 110 68 200

200-500 ft 2.5-5 ft 3.2 17 120 44 190

5-10 ft 6.3 58 460 250 770

10-20 ft 11 64 500 1,100 1,700

20-40 ft 0 0 0 880 880

200-500 ft total 20 140 1,100 2,300 3,500

>500 ft 2.5-5 ft 0 0.90 32 67 100

5-10 ft 0 0 14 140 150

10-20 ft 0 0 0 300 300

20-40 ft 0 0 0 470 470

>500 ft total 0 0.90 46 970 1,000

GOLDEN VALLEY total 21 160 1,200 3,300 4,800
Table WN-7. Hansen coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

HETTINGER 0-100 ft 5-10 ft 0 0 0.015 0.99 1.0

0-100 ft total 0 0 0.015 0.99 1.0

100-200 ft 2.5-5 ft 0 0 6.5 27 33

5-10 ft 0 0.31 61 110 170

10-20 ft 0 9.2 19 0 28

100-200 ft total 0 9.5 86 130 230

200-500 ft 2.5-5 ft 0.64 3.5 77 110 190

5-10 ft 3.5 32 410 550 1,000

10-20 ft 2.4 5.2 16 0 24

200-500 ft total 6.5 40 500 660 1,200

>500 ft 5-10 ft 0 0 0 42 42

>500 ft total 0 0 0 42 42

HETTINGER total 6.5 50 590 840 1,500

SLOPE 0-100 ft 2.5-5 ft 4.1 34 260 110 400

5-10 ft 18 120 610 420 1,200

10-20 ft 7.9 70 410 130 620

0-100 ft total 30 220 1,300 660 2,200

100-200 ft 2.5-5 ft 0.78 14 38 0.66 53

5-10 ft 10 67 260 68 410

10-20 ft 5.1 17 81 77 180

100-200 ft total 16 98 380 150 640

200-500 ft 2.5-5 ft 9.1 50 380 140 570

5-10 ft 18 130 920 410 1,500

10-20 ft 29 220 1300 130 1,700

20-40 ft 4.8 28 140 0 180

200-500 ft total 61 420 2,800 670 3,900

SLOPE total 130 860 5,000 1,700 7,600
Table WN-7. Hansen coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

STARK >500 ft 2.5-5 ft 0 0 1.1 61 62

5-10 ft 0 0 25 170 190

10-20 ft 0.64 22 220 5.6 250

>500 ft total 0.64 22 250 230 500

STARK total 0.64 22 250 230 500

Grand total (MST) 380 1,800 9,700 9,700 22,000
Table WN-8. Coal resources of the Hansen coal zone in the Bowman-Dickinson coalfield, Williston Basin, North

Dakota, reported by 7.5-minute quadrangle map area (see figure WN-5 and table WN-10). Resources are reported

in millions of short tons (MST) with two significant figures. Table does not include resources for coal less than 2.5

ft thick or coal in mine areas (fig. WN-7). Resource numbers will not sum to match total due to independent

rounding

7.5-minute quadrangle map Index map

number

Total

(MST)

7.5-minute quadrangle map Index map

number

Total

(MST)

ABBEY HILL 63 150 DEEP CREEK SOUTH 41 170

ALPHA 20 48 DRY BULLION CREEK 21 100

AMIDON 43 170 DUCK CREEK 11 59

AMIDON SE 57 610 EAST RAINY BUTTE 46 260

BARTHS BUTTE 85 300 EHLER LAKE 74 14

BEACH EAST 7 450 ENTERPRISE SCHOOL 61 2.3

BEACH WEST 6 280 FRYBURG 17 170

BLACK BUTTE 42 260 GASCOYNE 79 96

BOWMAN 68 90 GOLVA 19 13

BOYCE CREEK EAST 40 320 GRIFFIN 67 16

BOYCE CREEK WEST 39 160 HAVELOCK 48 45

BUCYRUS 81 44 HAYNES 90 140

BUFFALO GAP CAMPGROUND 9 250 HETTINGER NORTH 82 110

BULLION BUTTE 22 48 HETTINGER SOUTH 88 98

CARLYLE 18 11 HOOTOWL CREEK SW 4 250

CEDAR BUTTE 86 70 HOOTOWL CREEK WEST 1 0.08

CEDAR HILLS 65 110 IVES 54 500

CEDAR LAKE 60 190 JUNG LAKE 47 180

CHIMNEY BUTTE 15 1000 JUNIPER SPUR 31 670

CLIFFS PLATEAU 23 110 KID RICH BUTTE 89 230

COW BUTTE NE 87 0.14 LEFOR SW 37 0.15

DAGLUM 26 230 LEMMON 92 180

DAGLUM NW 25 350 LEMMON NE 93 2.7

DAGLUM SE 34 460 LIENS DAMS 62 200

DAGLUM SW 33 630 LONG BUTTE 77 0.79

DEEP CREEK NORTH 30 460 MARMARTH 52 41
Table WN-8. Hansen coal resources—continued

7.5-minute quadrangle map Index map

number

Total

(MST)

7.5-minute quadrangle map Index map

number

Total

(MST)

MARMARTH SE 53 530 SCRANTON SW 78 9.6

MEDORA 10 0.83 SENTINEL BUTTE 8 710

MINERAL SPRINGS 58 250 SENTINEL BUTTE SE 13 700

MOTT NORTH 51 6.8 SPRING CREEK 29 390

MOTT NW 50 190 SQUARE BUTTE 14 1,100

MOTT SW 64 6.5 STEWART LAKE 56 480

NEW ENGLAND 36 160 TALBOT BUTTE 69 230

NEW ENGLAND NW 27 49 TAYLOR BUTTE 75 0.094

NEW ENGLAND SW 35 400 TAYLOR BUTTE SE 83 450

ODLAND DAM 3 220 THELAN 12 350

ODLAND DAM NE 1 10 THREE V CROSSING 28 45

PEARL BUTTE 84 520 TRACY MOUNTAIN 16 810

PEARL BUTTE NW 76 11 WARNKE HILL 59 240

PRETTY BUTTE 38 9.0 WEST FORK DEEP CREEK 55 120

REEDER 80 260 WEST RAINY BUTTE 45 180

REGENT 49 260 WEST TWIN BUTTE 5 11

RHAME 66 140 WHETSTONE BUTTES 72 390

ROCKY RIDGE NORTH 24 250 WHITE BUTTE 91 180

ROCKY RIDGE SOUTH 32 740 WHITE LAKE 44 120

SCRANTON 70 200 WOLF BUTTE 73 120

SCRANTON NE 71 380 Grand total (MST) 22,000
Table WN-9. Hansen coal resources in the Bowman-Dickinsen coalfield, Williston Basin, North Dakota, reported

by Federal coal and surface ownership (fig. WN-6). Resources are shown in millions of short tons (MST) with 2

significant figures. The table does not include resources in mine areas or areas containing less than 2.5 ft of coal

(fig. WN-7). Resource numbers will not sum to match total due to independent rounding

Federal ownership Total (MST)

No Federal coal or surface ownership 13,000

No Federal coal, but Federal surface ownership 530

Federal coal, but no Federal surface ownership 5,800

Federal coal and surface ownership 2,000

Grand total (MST) 22,000
Table WN-10. Key to 7.5-minute quadrangle maps in the Hansen study limit (see figure WN-5 and table WN-8)

Number 7.5-minute quadrangle map Number 7.5-minute quadrangle map Number 7.5-minute quadrangle map

1 ODLAND DAM NE 32 ROCKY RIDGE SOUTH 63 ABBEY HILL

2 HOOTOWL CREEK WEST 33 DAGLUM SW 64 MOTT SW

3 ODLAND DAM 34 DAGLUM SE 65 CEDAR HILLS

4 HOOTOWL CREEK SW 35 NEW ENGLAND SW 66 RHAME

5 WEST TWIN BUTTE 36 NEW ENGLAND 67 GRIFFIN

6 BEACH WEST 37 LEFOR SW 68 BOWMAN

7 BEACH EAST 38 PRETTY BUTTE 69 TALBOT BUTTE

8 SENTINEL BUTTE 39 BOYCE CREEK WEST 70 SCRANTON

9 BUFFALO GAP CAMPGROUND 40 BOYCE CREEK EAST 71 SCRANTON NE

10 MEDORA 41 DEEP CREEK SOUTH 72 WHETSTONE BUTTES

11 DUCK CREEK 42 BLACK BUTTE 73 WOLF BUTTE

12 THELAN 43 AMIDON 74 EHLER LAKE

13 SENTINEL BUTTE SE 44 WHITE LAKE 75 TAYLOR BUTTE

14 SQUARE BUTTE 45 WEST RAINY BUTTE 76 PEARL BUTTE NW

15 CHIMNEY BUTTE 46 EAST RAINY BUTTE 77 LONG BUTTE

16 TRACY MOUNTAIN 47 JUNG LAKE 78 SCRANTON SW

17 FRYBURG 48 HAVELOCK 79 GASCOYNE

18 CARLYLE 49 REGENT 80 REEDER

19 GOLVA 50 MOTT NW 81 BUCYRUS

20 ALPHA 51 MOTT NORTH 82 HETTINGER NORTH

21 DRY BULLION CREEK 52 MARMARTH 83 TAYLOR BUTTE SE

22 BULLION BUTTE 53 MARMARTH SE 84 PEARL BUTTE

23 CLIFFS PLATEAU 54 IVES 85 BARTHS BUTTE

24 ROCKY RIDGE NORTH 55 WEST FORK DEEP CREEK 86 CEDAR BUTTE

25 DAGLUM NW 56 STEWART LAKE 87 COW BUTTE NE

26 DAGLUM 57 AMIDON SE 88 HETTINGER SOUTH

27 NEW ENGLAND NW 58 MINERAL SPRINGS 89 KID RICH BUTTE

28 THREE V CROSSING 59 WARNKE HILL 90 HAYNES

29 SPRING CREEK 60 CEDAR LAKE 91 WHITE BUTTE

30 DEEP CREEK NORTH 61 ENTERPRIZE SCHOOL 92 LEMMON

31 JUNIPER SPUR 62 LIENS DAMS 93 LEMMON NE
Table WN-11. Data used for computation of confidence intervals within reliability categories for Hansen coal

resources in the Bowman-Dickinson coalfield, Williston Basin, North Dakota. Volume refers to the calculated

resource in millions of short tons (MST). NA, not applicable

Parameter Reliability category Entire

Measured Indicated Inferred Hypothetical area

Area (in square meters) 123,667,036 593,688,851 3,286,461,611 2,693,673,550 6,697,491,047

Percent of area 2 9 49 40 100

Acres (area x 0.0002471) 30,559 146,704 812,102 665,621 1,654,986

SD (standard deviation (in ft) from

semivariogram model)

2.16 2.45 3.41 4.01 NA

Acre feet (Acres x SD) 65,844 359,567 2,769,859 2,670,629 NA

Volume standard deviation (MST) 7 56 732 4,727 5,522

Pseudo n 243 130 45 1 NA

Table WN-12. Estimates of uncertainty (calculated with measurement error) for Hansen coal resources in the

Bowman-Dickinson coalfield, Williston Basin, North Dakota. To show detail, resources are reported in millions of

short tons (MST) with four significant figures

Parameter Reliability category Entire

Measured Indicated Inferred Hypothetical area

Total calculated resource (MST) 382.6 1,846 9,743 9,669 21,640

Lower 90% confidence limit (MST) 370.0 1,754 8,539 1,893 12,560

Upper 90% confidence limit (MST) 395.0 1,938 10,950 17,450 30,730
Table WN-13. Coal resources of the Beulah-Zap coal zone in the Beulah coalfield, Williston Basin, North Dakota,

reported by overburden (fig. WN-12), net coal thickness (fig. WN-11), and reliability categories. Zeros (0) indicate

areas where no resources were calculated. Table does not include resources for coal less than 2.5 ft, in mine areas,

or in areas containing Beulah-Zap clinker (fig. WN-11). Resources are reported in millions of short tons (MST)

with two significant figures. Resource numbers will not sum to match totals due to independent rounding

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

MCLEAN 0-100 ft 2.5-5 ft 8.3 18 6.5 0 33

5-10 ft 40 100 23 0 170

10-20 ft 87 180 28 0 290

0-100 ft total 130 300 58 0 490

100-200 ft 2.5-5 ft 2.8 13 3.9 0 20

5-10 ft 22 76 35 0 130

10-20 ft 23 74 31 0 130

100-200 ft total 48 160 69 0 280

200-500 ft 2.5-5 ft 0.83 0.31 0 0 1.1

5-10 ft 1.2 6.2 7.7 0 15

10-20 ft 0.24 0.49 0 0 0.73

200-500 ft total 2.2 7 7.7 0 17

MCLEAN total 180 470 130 0 790

MERCER 0-100 ft 2.5-5 ft 13 26 27 3.8 70

5-10 ft 110 110 130 63 410

10-20 ft 310 210 390 310 1,200

20-40 ft 75 35 18 0 130

>40 ft 0.31 0 0 0 0.31

0-100 ft total 510 380 560 380 1,800

100-200 ft 2.5-5 ft 3.4 2.3 28 2.4 36

5-10 ft 31 50 18 15 110

10-20 ft 220 190 320 130 870
Table WN-13. Beulah-Zap coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

MERCER 100-200 ft 20-40 ft 62 72 150 0 280

100-200 ft total 320 320 510 150 1,300

200-500 ft 2.5-5 ft 0.15 0.24 2.4 0 2.8

5-10 ft 5.1 4.3 11 0 20.0

10-20 ft 19 37 41 24 120

20-40 ft 6.4 34 94 0 130

200-500 ft total 31 75 150 24 280

MERCER total 860 770 1,200 550 3,400

MORTON 0-100 ft 5-10 ft 0.38 0.26 0 0 0.64

0-100 ft total 0.38 0.26 0 0 0.64

100-200 ft 5-10 ft 0.40 1.7 0 0 2.1

100-200 ft total 0.40 1.7 0 0 2.1

200-500 ft 5-10 ft 0 0.13 0 0 0.13

200-500 ft total 0 0.13 0 0 0.13

MORTON total 0.78 2.1 0 0 2.8

OLIVER 0-100 ft 2.5-5 ft 7.5 4.9 3.4 0 16

5-10 ft 28 47 42 0 120

10-20 ft 31 7.2 0.37 0 39

20-40 ft 0.79 0.39 0 0 1.2

0-100 ft total 67 59 46 0 170

100-200 ft 2.5-5 ft 3.0 5.9 11 0 20

5-10 ft 25 110 68 0 210

10-20 ft 20.0 69 36 0 120

100-200 ft total 48 190 110 0 350

200-500 ft 2.5-5 ft 1.1 4.7 0.69 0 6.5

5-10 ft 7.3 47 20 0 75
Table WN-13. Beulah-Zap coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

OLIVER 200-500 ft 10-20 ft 5.7 21 6.4 0 34

200-500 ft total 14 73 27 0 110

OLIVER total 130 320 190 0 640

Grand total (MST) 1,200 1,600 1,500 550 4,800

Table WN-14. Coal resources of the Beulah-Zap coal zone in the Beulah coalfield, Williston Basin, North Dakota,

reported by 7.5-minute quadrangle (fig. WN-9) map area. Resources are reported in millions of short tons (MST)

with two significant figures. The table does not include resources for coal less than 2.5 ft thick, in mine areas, or in

areas containing Beulah-Zap clinker (fig. WN-11). Resource numbers will not sum to match total due to

independent rounding

7.5-minute quadrangle

map

Total

(MST)

7.5-minute quadrangle

map

Total

(MST)

7.5-minute quadrangle

map

Total

(MST)

BEULAH 330 GLEN ULLIN NE 34 MEDICINE BUTTE NE 79

BEULAH NE 240 GLEN ULLIN NW 22 MEDICINE BUTTE SE 300

BEULAH NW 590 GOLDEN VALLEY 180 MEDICINE BUTTE SW 210

BLACKWATER LAKE 6.0 GOLDEN VALLEY NE 230 OTTER CREEK 74

BLUE HILL 42 HAILSTONE BUTTE 29 RED BUTTE 48

DOUGLAS EAST 92 HANNOVER NW 3.5 RED BUTTE NW 30

DOUGLAS WEST 120 HANNOVER NW 3.5 RED BUTTE SW 400

EMMET 14 HAZEN EAST 22 ROSEGLEN 41

EMMET NE 120 HAZEN NE 140 SCHAFFNER CREEK NE 15

EMMET SE 35 HAZEN NW 190 WILLOW CREEK EAST 46

GARRISON 280 HAZEN WEST 140 ZAP 560

GARRISON DAM NORTH 44 MEDICINE BUTTE 130 Grand total (MST) 4,800
Table WN-15. Beulah-Zap coal resources in the Beulah coalfield, Williston Basin, North Dakota, reported by

Federal coal and surface ownership (fig. WN-10). Resources are shown in millions of short tons (MST) with two

significant figures. The table does not include resources for coal less than 2.5 ft thick, in mine areas, or in areas

containing Beulah-Zap clinker (fig. WN-11). Resource numbers will not sum to match total due to independent

rounding

Federal ownership Total (MST)

No Federal coal or surface ownership 3,400

Federal coal ownership, but no Federal surface ownership 1,400

Grand total (MST) 4,800
Table WN-16. Data used for computation of confidence intervals within reliability categories for Beulah-Zap coal

resources in the Beulah coalfield, Williston Basin, North Dakota. Volume refers to the calculated resource in millions

of short tons (MST). NA, not applicable

Parameter Reliability category Entire

Measured Indicated Inferred Hypothetical area

Area (in square meters) 237,120,736 368,807,104 314,035,128 120,633,512 1,040,596,479

Percent of area 23 35 30 12 100

Acres (area x 0.0002471) 58,594 91,134 77,600 29,809 257,137

SD (standard deviation (in ft) from

residual thickness)

4.132 4.132 4.132 4.132 NA

Acre feet (acres x SD) 242,110 376,567 320,642 123,172 NA

Volume standard deviation (MST) 20 74 274 218 586

Pseudo n 466 81 4 1 NA

Table WN-17. Estimates of uncertainty (calculated with measurement error) for Beulah-Zap coal resources in the

Beulah coalfield, Williston Basin, North Dakota. To show detail, resources calculations are in millions of short

tons (MST) with four significant figures

Parameter Reliability category Entire

Measured Indicated Inferred Hypothetical area

Total calculated resource (MST) 1,172 1,561 1,546 551.4 4,830

Lower 90% confidence limit (MST) 1,139 1,439 1,095 193.0 3,866

Upper 90% confidence limit (MST) 1,205 1,683 1,997 910.0 5,794
Table WN-18. Coal resources of the Hagel coal zone in the Center-Falkirk coalfield, Williston Basin, North

Dakota, reported by overburden (fig. WN-16), net coal thickness (fig. WN-15), and reliability categories. Zeros (0)

indicate areas where no resources were calculated. Table does not include resources for coal less than 2.5 ft thick or

coal in mine areas (fig. WN-15). Resources are reported in millions of short tons (MST) with two significant

figures. Resource numbers will not sum to match totals due to independent rounding

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

MCLEAN 0-100 ft 2.5-5 ft 21 25 4.7 0 50.0

5-10 ft 130 120 25 0 270

10-20 ft 120 69 5.7 0 190

0-100 ft total 270 210 35 0 510

100-200 ft 2.5-5 ft 7.3 10.0 5.8 0 23

5-10 ft 29 47 13 0 89

10-20 ft 23 57 15 0 95

100-200 ft total 59 110 35 0 210

MCLEAN total 330 320 70.0 0 720

MERCER 0-100 ft 2.5-5 ft 4.5 15 5.1 0 25

5-10 ft 9.7 10.0 23 0 43

10-20 ft 56 30.0 28 0.29 110

20-40 ft 14 35 17 0 66

0-100 ft total 84 90.0 74 0.29 250

100-200 ft 2.5-5 ft 10 25 39 1.8 77

5-10 ft 12 41 66 0 120

10-20 ft 51 23 94 0 170

20-40 ft 6.4 26 25 0 57

100-200 ft total 80 120 220 1.8 420
Table WN-18. Hagel coal resources—continued

County Overburden Net coal Reliability category (distance from data point) Grand total

thickness thickness Measured

(<1/4 mi)

Indicated

(1/4-3/4 mi)

Inferred

(3/4-3 mi)

Hypothetical

(>3 mi)

 (MST)

MERCER 200-500 ft 2.5-5 ft 4.5 22 89 9.7 130

5-10 ft 2.9 14 98 0 110

10-20 ft 4.6 2.6 42 0 49

20-40 ft 3.4 5.0 3.0 0 12

200-500 ft total 15 43 230 9.7 300

MERCER total 180 250 530 12 970

OLIVER 0-100 ft 2.5-5 ft 16 4.4 0 0 20.0

5-10 ft 100 46 1.0 0 150

10-20 ft 430 260 22 0 710

20-40 ft 56 40 2.1 0 98

0-100 ft total 600 350 25 0 970

100-200 ft 2.5-5 ft 4.1 4.3 3.8 0 12

5-10 ft 23 52 28 0 100

10-20 ft 310 380 110 0 800

20-40 ft 53 89 18 0 160

100-200 ft total 390 520 160 0 1,100

200-500 ft 2.5-5 ft 7.1 22 17 0 47

5-10 ft 32 71 93 0 200

10-20 ft 34 140 120 0 300

20-40 ft 6.4 71 45 0 120

>40 ft 1.7 0 0 0 1.7

200-500 ft total 81 300 280 0 660

OLIVER total 1,100 1,200 460 0 2,700

Grand total (MST) 1,600 1,700 1,100 12 4,400
Table WN-19. Coal resources of the Hagel coal zone in the Center-Falkirk coalfield, Williston Basin, North

Dakota, reported by 7.5-minute quadrangle (fig. WN-13). Resources are reported in millions of short tons (MST)

with two significant figures. Table does not include resources for coal less than 2.5 ft thick or coal in mine areas

(fig. WN-15). Resource numbers will not sum to match total due to independent rounding

7.5-minute quadrangle

map

Total

(MST)

7.5-minute quadrangle

map

Total

(MST)

7.5-minute quadrangle

map

Total

(MST)

BEULAH 3.3 HAZEN EAST 41 RIVERDALE NORTH 7.3

BEULAH NE 65 HAZEN NE 130 RIVERDALE SOUTH 44

CENTER 210 HAZEN NW 350 STANTON 180

COLEHARBOR 85 HAZEN WEST 71 STANTON SE 69

EMMET SW 17 LAKE NETTIE 100 TURTLE CREEK NW 27

FORT CLARK 260 NELSON LAKE 67 UNDERWOOD 120

GARRISON DAM SOUTH 24 OTTER CREEK 190 WASHBURN 0.22

HANNOVER 380 RED BUTTE 290 WASHBURN NE 220

HANNOVER NE 430 RED BUTTE NW 34 WASHBURN SW 42

HANNOVER NW 940 RED BUTTE SW 2.0 Grand total (MST) 4,400

Table WN-20. Hagel coal resources in the Center-Falkirk coalfield, Williston Basin, North Dakota, reported by

Federal coal and surface ownership (fig. WN-14). Resources are shown in millions of short tons (MST) with 2

significant figures. The table does not include resources in mine areas or areas containing less than 2.5 ft of coal.

Resource numbers will not sum to match total due to independent rounding

Federal ownership Total (MST)

No Federal coal or surface ownership 3,600

Federal coal, but no Federal surface ownership 760

Grand total (MST) 4,400
Table WN-21. Data used for computation of confidence intervals within reliability categories for Hagel coal

resources in the Center-Falkirk coalfield, Williston Basin, North Dakota. Volume refers to the calculated resource in

millions of short tons (MST). NA, not applicable

Parameter Reliability Category Entire

Measured Indicated Inferred Hypothetical Area

Area (in square meters) 335,432,395 389,435,954 303,702,006 6,609,852 1,035,180,207

Percent of area 32 38 29 1 100

Acres (area x 0.0002471) 82,887 96,232 75,046 1,633 255,799

SD (standard deviation (in ft) from

semivariogram model)

4.295 5.088 6.403 6.762 NA

Acre feet (acres x SD) 355,982 489,643 480,516 11,045 NA

Volume standard deviation (MST) 25 94 418 20 556

Pseudo n 660 85 4 1 NA

Table WN-22. Estimates of uncertainty (calculated with measurement error) for the Hagel coal resources in the

Center-Falkirk coalfield, Williston Basin, North Dakota with measurement error. To show detail, resources are

reported in millions of short tons (MST) with four significant figures

Parameter Reliability category Entire

Measured Indicated Inferred Hypothetical area

Total calculated resource (MST) 1,585 1,746 1,057 11.77 4,401

Lower 90% confidence limit (MST) 1,544 1,592 371.0 0.000 3,487

Upper 90% confidence limit (MST) 1,625 1,901 1,745 44.00 5,315