Estimated Gravel Resources of the Soucook River Valley, Loudon, New Hampshire, 7.5' Quadrangle Using Improved Techniques for Assessing Gravel Resources in Glaciofluvial Deposits

Eastern Mineral Resources

Sutphin, D.M., Drew, L.J., Fowler, B.K., 1999, Estimated gravel resources of the Soucook River valley, Loudon, New Hampshire, 7.5' Quadrangle using improved techniques for assessing gravel resources in glaciofluvial deposits [abstr.]: Geological Society of America, Program with Abstracts, Northeastern Section 34 th annual meeting, v. 31, no. 2, p. 71

Estimated Gravel Resources of the Soucook River Valley, Loudon, New Hampshire, 7.5' Quadrangle Using Improved Techniques for Assessing Gravel Resources in Glaciofluvial Deposits

By David M. Sutphin¹, Lawrence J. Drew¹, and Brian K. Fowler²
¹U.S. Geological Survey, 954 National Center, Reston, Virginia 20192
²North American Reserve, 67 Water Street, Suite 207, Laconia, New Hampshire 03246

Contents: Estimates of Sand-and-Gravel Resources in Esker Deposits | Estimates of Sand-and-Gravel Resources in Nonesker Deposits | Examples of Input and Output Data in the Geographic Information System (GIS) Geology

Abstract

A new method based upon surficial mapping techniques that use the morphosequence concept and geographic information systems (GIS) has been developed for estimating the sand and gravel resources in glaciofluvial systems. Two different strategies were used to estimate the gravel resources. One strategy estimates the sand and gravel resources contained in esker deposits; the other, which is more reliant on GIS, estimates those resources in nonesker deposits. An attempt has been made to determine which deposits have been sterilized; that is, those beneath the water table, adjacent to streams or roads, or encroached by urbanization. By using this method preliminary estimates indicate that about 158 x 10⁶ m³ of sand and gravel is in the Soucook River Valley part of the Loudon, NH, 7.5' quadrangle. About 65 x 10⁶ m³ of these materials are in deposits above the water table. About 34 percent of the sand and gravel resources are unlikely to be mined, because they have been sterilized. Of the remaining resources, 0.48 x 10⁶ m³ of gravel and 1.1 x 10⁶ m³ of sand are in esker deposits, and 9.0 x 10⁶ m³ of gravel and 37 x 10⁶ m³ of sand are in stratified nonesker deposits. With the addition of new well data, newer and more-accurate estimates will be possible.

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Estimates of Sand-and-Gravel Resources in Esker Deposits

Sand and gravel resources in eskers were estimated separately from other glaciofluvial deposits because eskers are easily identifiable on geologic and topographic maps and in the field. Because eskers are often raised topographic features, much of their resources can be gotten before encroaching on the water table. Once the volume of an esker's resources was determined, estimates were made for the amounts of those materials that could not be exploited because they coincided with sterilized areas, such as stream or road buffers, previous quarrying, housing, or other permanent construction. This was done by determining the area that had beeen sterilized, estimating the thickness of the eskers in that area, calculating the volume of the gravel resources in the sterilized area, and subtracting that volume from the total for the esker. In this way, the total exploitable sand and gravel resources were found for each esker. These totals are shown in the table below.

map of study area index map

Study area - Part of the 1:24,000 geologic map of the Loudon quadrangle (Goldsmith, written commun.) showing esker deposits (dark green), aligned like beads on a string, in the Soucook River Valley. Number denotes the esker number in the table below.

Photograph illustrating an esker that has been quarried.
Photograph of the north face of an esker being consumed for sand and gravel resources in the Loudon, NH, quadrangle. About 1,000 ft of the esker have been removed. Resources below the horizontal surface at the foot of the esker have been sterilized because they are encroaching the water table.

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Estimated in-place and sterilized sand and gravel resources in esker deposits in the Soucook River Valley part of the Loudon quadrangle. (Sand and gravel in eskers 4 and 5 have been removed by previous mining.)
Esker No. In-place resources (m³) Sterile resources (m³) Exploitable resources (m³) Sand (yd³) Gravel (yd³) Sand (st) Gravel (st)

1 17,300 5,240 12,100 11,100 4,750 13,300 7,120

2 151,500 71,100 80,400 73,600 31,500 88,300 47,300

3 122,000 879 121,000 111,000 47,600 133,000 71,400

4 0 0 0 0 0 0 0

5 0 0 0 0 0 0 0

6 91,800 8,420 83,300 76,300 32,700 91,600 49,100

7 487,000 0 487,000 446,000 191,000 535,000 287,000

8 625,000 54,300 570,000 522,000 224,000 627,000 336,000

9 288,000 85,000 203,000 186,000 79,700 223,000 119,000

10 77,000 72,600 4,350 4,000 1,710 4,780 2,560

11 285,000 248,000 36,600 33,500 14,400 40,300 21,600

Total 2,140,000 546,000 1,600,000 1,460,000 627,000 1,760,000 941,000

Conversion factors (m, meter; ft, foot; yd, yard; st, short ton):
1 m³ = 35.3147 ft³ = 1.30795 yd³
1 yd³ gravel = 1.5 st gravel
1 yd³ sand = 1.2 st sand

Estimated in-place and sterilized sand and gravel resources in esker deposits in the Soucook River Valley part of the Loudon quadrangle. (Sand and gravel in eskers 4 and 5 have been removed by previous mining.)
Esker No.	In-place resources (m³)	Sterile resources (m³)	Exploitable resources (m³)	Sand (yd³)	Gravel (yd³)	Sand (st)	Gravel (st)
1	17,300	5,240	12,100	11,100	4,750	13,300	7,120
2	151,500	71,100	80,400	73,600	31,500	88,300	47,300
3	122,000	879	121,000	111,000	47,600	133,000	71,400
4	0	0	0	0	0	0	0
5	0	0	0	0	0	0	0
6	91,800	8,420	83,300	76,300	32,700	91,600	49,100
7	487,000	0	487,000	446,000	191,000	535,000	287,000
8	625,000	54,300	570,000	522,000	224,000	627,000	336,000
9	288,000	85,000	203,000	186,000	79,700	223,000	119,000
10	77,000	72,600	4,350	4,000	1,710	4,780	2,560
11	285,000	248,000	36,600	33,500	14,400	40,300	21,600
Total	2,140,000	546,000	1,600,000	1,460,000	627,000	1,760,000	941,000

Conversion factors (m, meter; ft, foot; yd, yard; st, short ton): 1 m³ = 35.3147 ft³ = 1.30795 yd³ 1 yd³ gravel = 1.5 st gravel 1 yd³ sand = 1.2 st sand

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Estimates of Sand-and-Gravel Resources in Nonesker Deposits

Cross section showing relation of surface, water table and bottom of deposit Cross section showing the relation among the topographic surface, the water table surface, and surface of the bottom of the sand and gravel deposits.

The approach taken to estimate the sand and gravel resources in nonesker deposits consisted of several steps, each of which used GIS. The geologic map was used to define the area expected to contain glaciofluvial gravel resources, which was mostly the footprint of glacial Lake Hooksett. Much of the quadrangle was omitted because the glacio-fluvial system was confined to the valley floor. Areas outside of the valley floor are unlikely to contain sand and gravel deposits, because the rock type is glacial till.

Schematic showing the various parts of the GIS that were used to estimate resources Schematic showing how the various parts of the GIS were used to estimate the sand and gravel resources in the Soucook River Valley part of the Loudon quadrangle.

Digital lattices were created that represent the following stratigraphic surfaces in the study area: topography, water table, bottom of the sand and gravel deposits, percent gravel, and sterilization. The elevation of the bottom of the sand and gravel deposits was subtracted from the topography to give the thickness of the deposits. Where the water table was above the bottom of the deposits, the elevation was subtracted to give the thickness of the deposits above the water table. The thickness of the deposits was multipied by the percent gravel to yield the amount of gravel in the deposits above the water table. Finally, the sterilization map was used as a mask to keep sterilzed deposits from being counted as resources.

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Estimated sand and gravel resources in glaciofluvial deposits in the Soucook River Valley part of the Loudon quadrangle
Category Total Resources Sand Gravel Sand Gravel

Cubic meters Cubic yards (yd³) (yd³) (st) (st)

Part 1 totals:
Nonsterile sand
and gravel in eskers 1,600,000 2,090,000 1,460,000 627,000 1,760,000 941,000

Part 2 totals:
Nonsterile gravel
above water table 8,950,000 11,700,000 0 11,700,000 0 17,600,000

Nonsterile sand
above water table 37,200,000 48,600,000 48,600,000 0 58,400,000 0

Parts 1 and 2 totals: 47,700,000 62,400,000 50,100,000 12,300,000 60,100,000 18,500,000

Total nonsterile
sand and gravel above
the water table 46,100,000 60,300,000 48,600,000 11,700,000 58,400,000 17,600,000

Total sand and gravel
above the water table including
all the eskers regardless
of sterilization 64,500,000 84,400,000 67,800,000 16,700,000 81,300,000 24,900,000

Conversion factors (m, meter; ft, foot; yd, yard; st, short ton):
1 m³ = 35.3147 ft³ = 1.30795 yd³
1 yd³ gravel = 1.5 st gravel
1 yd³ sand = 1.2 st sand

Estimated sand and gravel resources in glaciofluvial deposits in the Soucook River Valley part of the Loudon quadrangle
Category	Total Resources	Sand	Gravel	Sand	Gravel
	Cubic meters	Cubic yards	(yd³)	(yd³)	(st)	(st)
Part 1 totals: Nonsterile sand and gravel in eskers	1,600,000	2,090,000	1,460,000	627,000	1,760,000	941,000
Part 2 totals: Nonsterile gravel above water table	8,950,000	11,700,000	0	11,700,000	0	17,600,000
Nonsterile sand above water table	37,200,000	48,600,000	48,600,000	0	58,400,000	0
Parts 1 and 2 totals:	47,700,000	62,400,000	50,100,000	12,300,000	60,100,000	18,500,000
Total nonsterile sand and gravel above the water table	46,100,000	60,300,000	48,600,000	11,700,000	58,400,000	17,600,000
Total sand and gravel above the water table including all the eskers regardless of sterilization	64,500,000	84,400,000	67,800,000	16,700,000	81,300,000	24,900,000

Conversion factors (m, meter; ft, foot; yd, yard; st, short ton): 1 m³ = 35.3147 ft³ = 1.30795 yd³ 1 yd³ gravel = 1.5 st gravel 1 yd³ sand = 1.2 st sand

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Examples of Input and Output Data in the Geographic Information System (GIS)

geologic map topographic map

Geologic Map - The geologic map (Goldsmith, written commun.) was used to define where (and where not) glaciofluvial deposits occur in the Loudon quadrangle.
Click here to download a Post Script copy of the map (2.7 Mb)
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Topography - A digital elevation model (DEM) of the Loudon quadrangle was downloaded from the USGS internet site and used to represent the land surface. The 20-ft contours are from the topographic map.
Click here to download a Post Script copy of the map (1.6 Mb)

sand & gravel thickness surface of water table

Sand and Gravel Thickness - Shaded relief map showing the estimated thickness of sand and gravel deposits in the Soucook River Valley part of the Loudon quadrangle. Deposits range from 2 to more than 72 ft thick.
Click here to download a Post Script copy of the map (2.2 Mb)
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Surface of the Water Table (10-ft contours) - Map showing the surface of the water table at 10-ft contours (blue) in the Soucook River Valley part of the Loudon quadrangle. The surface was developed from well data and stream elevations.
Click here to download a Post Script copy of the map (1.1 Mb)

percent gravel surface locations of water wells

Percent Gravel Surface - Shaded relief map showing gravel percentages for areas in the Soucook River Valley. Percentages range to as much as 40 percent and were estimated from water-well data. The relief map is overlain with streams and stream buffers.
Click here to download a Post Script copy of the map (6.5 Mb)
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Locations of Water Wells - Map showing locations of water wells in the Loudon quadrangle. Data from water wells was used to determine the thickness and approximate percentage of sand and gravel in glaciofluvial deposits that they penetrated. Sterilized areas are in red.
Click here to download a Post Script copy of the map (2.0 Mb)

sterile areas sand & gravel resources

Sterilized Areas - Map showing roads, streams, and their buffer zones, and urbanized areas. These areas were excluded from the resource estimates because of the small likelihood that the sand and gravel resources in them would be mined.
Click here to download a Post Script copy of the map (1.0 Mb) Non-Sterilized Areas Having Sand and Gravel Resources - Shaded relief map of the Soucook River Valley part of the Loudon quadrangle showing the thickness of the sand and gravel deposits. Nonsterilized areas are in red.
Click here to download a Post Script copy of the map (2.2 Mb)

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Return to: USGS - Geologic Information - Mineral Resources Program - Eastern Mineral Resources Team

This page is URL: https://pubs.usgs.gov/posters/NH_gravel/
Maintained by Eastern Publications Group Webteam
Last modified 09.20.00 (jmw)


	Study area - Part of the 1:24,000 geologic map of the Loudon quadrangle (Goldsmith, written commun.) showing esker deposits (dark green), aligned like beads on a string, in the Soucook River Valley. Number denotes the esker number in the table below.

	Photograph of the north face of an esker being consumed for sand and gravel resources in the Loudon, NH, quadrangle. About 1,000 ft of the esker have been removed. Resources below the horizontal surface at the foot of the esker have been sterilized because they are encroaching the water table.


Geologic Map - The geologic map (Goldsmith, written commun.) was used to define where (and where not) glaciofluvial deposits occur in the Loudon quadrangle. Click here to download a Post Script copy of the map (2.7 Mb) Return to top	Topography - A digital elevation model (DEM) of the Loudon quadrangle was downloaded from the USGS internet site and used to represent the land surface. The 20-ft contours are from the topographic map. Click here to download a Post Script copy of the map (1.6 Mb)

Sand and Gravel Thickness - Shaded relief map showing the estimated thickness of sand and gravel deposits in the Soucook River Valley part of the Loudon quadrangle. Deposits range from 2 to more than 72 ft thick. Click here to download a Post Script copy of the map (2.2 Mb) Return to top	Surface of the Water Table (10-ft contours) - Map showing the surface of the water table at 10-ft contours (blue) in the Soucook River Valley part of the Loudon quadrangle. The surface was developed from well data and stream elevations. Click here to download a Post Script copy of the map (1.1 Mb)

Percent Gravel Surface - Shaded relief map showing gravel percentages for areas in the Soucook River Valley. Percentages range to as much as 40 percent and were estimated from water-well data. The relief map is overlain with streams and stream buffers. Click here to download a Post Script copy of the map (6.5 Mb) Return to top	Locations of Water Wells - Map showing locations of water wells in the Loudon quadrangle. Data from water wells was used to determine the thickness and approximate percentage of sand and gravel in glaciofluvial deposits that they penetrated. Sterilized areas are in red. Click here to download a Post Script copy of the map (2.0 Mb)

Sterilized Areas - Map showing roads, streams, and their buffer zones, and urbanized areas. These areas were excluded from the resource estimates because of the small likelihood that the sand and gravel resources in them would be mined. Click here to download a Post Script copy of the map (1.0 Mb)	Non-Sterilized Areas Having Sand and Gravel Resources - Shaded relief map of the Soucook River Valley part of the Loudon quadrangle showing the thickness of the sand and gravel deposits. Nonsterilized areas are in red. Click here to download a Post Script copy of the map (2.2 Mb)