including clamshell buckets, backhoes, dustpan, and
cutterhead suction dredges (see Dredging). The hydraulic
approaches require dewatering of the sand-water slurry
but can achieve higher rates and facilitate transport by
allowing pumping through long pipelines to desired discharge points. Terrestrial deposits can likewise be excavated by a wide variety of techniques, but most are
classified as surface mining, digging from the top of the
deposit downward, continually excavating the exposed
surface of the deposit.
Summary
Sand mining is a major, global industry and will remain
important for many years to come. It has been utilized historically to acquire building and industrial supplies, but
new applications arise over time, such as excavation of
tar sands for their energy value and the mining of frac
sands for use in hydraulic fracking operations to extract
subterranean hydrocarbons. Likewise, new environmental
issues to be mitigated are likely to continue to arise. Terrestrial sand mining in particular tends to lead to protests
from citizens concerned with land use and environmental
issues, because it often results in highly visible, permanent
changes to the landscape. The western Great Lakes region
in the United States (Wisconsin, Minnesota), for example,
is the source of a large amount of sand being used for
fracking operations and is dealing with public protests
over the mining of these materials.
Bibliography
Finkl, C. W., and Hobbs, C. H., III, 2009. Mining sand on the continental shelf of the Atlantic and Gulf Coasts of the U.S. Marine
Georesources and Geotechnology, 27, 230–253.
Kosmatka, S. H., and Wilson, M. L., 2011. Design and Control of Concrete Mixtures, 15th edn. Skokie, IL: Portland Cement Association.
Meador, M. R., and Layher, A. O., 1998. Instream sand and gravel
mining: environmental issues and regulatory processes in the
United States. Fisheries, 23(11), 6–13.
Cross-references
Anthropogenic Impacts
Dredge and Fill
Dredging
Mass Physical Sediment Properties
SAND RIDGE
Marci M. Robinson
US Geological Survey, Eastern Geology and Paleoclimate
Science Center, Reston, VA, USA
Synonyms
Linear shoal; Sand shoal; Shoreface ridge; Tidal current
ridge
Definition
Sand ridges are elongate coastal or shelf sand bodies that
form bathymetric highs on the seafloor (Duane et al., 1972).
Description
Sand ridges are asymmetrical features composed of
unconsolidated fine to coarse sand and gravel. They are
typically 5-120 km long and 0.5-8 km wide, with heights
of more than 20 % of the water depth and slopes of less
than 1
. They occur on continental shelves in a wide range
of water depths, where sufficient sand exists and currents
are strong enough to transport sand-sized sediment. They
also usually occur in groups that are shore parallel, shore
oblique, or shore normal, with spacing between members
of $250 times the water depth, along topographically
irregular transgressive margins (Snedden and Dalrymple,
1999). Based on the relative progression of ridge
reworking and migration (Snedden and Dalrymple,
1999), sand ridges belong to one of three classes. Class
I ridges are young ridges that maintain their original
nucleus and are at or near their point of origination. Class
II ridges are partially evolved ridges that have maintained
some of their original nucleus and have migrated
a distance less than their original width. Class III ridges
are fully evolved forms that have maintained none of their
original nucleus. They have migrated a distance greater
than or equal to their original width.
Several hypotheses and models have been developed
that address the origin of sand ridges; these are largely
based on their distribution and orientation. They include
(1) the drowning of static, pre-transgressive features such
as barrier islands, beach ridges, and interfluves (e.g.,
Veatch and Smith, 1939); (2) the formation of posttransgressive features in equilibrium with the hydraulic
regime (e.g., Uchupi, 1968) or formed during storms
(e.g., Duane et al., 1972; Swift and Field, 1981); and
(3) the reworking of modern features associated with an
actively transgressing shoreline (e.g., Swift and Field,
1981; Robinson and McBride, 2008).
Bibliography
Duane, D. B., Field, M. E., Meisburger, E. P., Swift, D. J. P., and
Williams, S. J., 1972. Linear shoals on the Atlantic inner continental shelf, Florida to Long Island. In Swift, D. J. P., Duane,
D. B., and Pilkey, O. H. (eds.), Shelf Sediment Transport: Process
and Pattern. Stroudsburg: Dowden, Hutchinson, and Ross,
pp. 447–498.
Robinson, M. M., and McBride, R. A., 2008. Anatomy of
a shoreface sand ridge revisited using foraminifera: False Cape
Shoals, Virginia/North Carolina inner shelf. Continental Shelf
Research, 28, 2428–2441.
Snedden, J. W., and Dalrymple, R. W., 1999. Modern shelf sand
ridges: from historical perspective to a unified hydrodynamic
and evolutionary model. In Bergman, K. M., and Snedden,
J. W. (eds.), Isolated Shallow Marine Sand Bodies: Sequence
Stratigraphic Analysis and Sedimentologic Interpretation.
Tulsa, OK: SEPM, Special Publication 64, pp. 13–28.
536
SAND RIDGE
cutterhead suction dredges (see Dredging). The hydraulic
approaches require dewatering of the sand-water slurry
but can achieve higher rates and facilitate transport by
allowing pumping through long pipelines to desired discharge points. Terrestrial deposits can likewise be excavated by a wide variety of techniques, but most are
classified as surface mining, digging from the top of the
deposit downward, continually excavating the exposed
surface of the deposit.
Summary
Sand mining is a major, global industry and will remain
important for many years to come. It has been utilized historically to acquire building and industrial supplies, but
new applications arise over time, such as excavation of
tar sands for their energy value and the mining of frac
sands for use in hydraulic fracking operations to extract
subterranean hydrocarbons. Likewise, new environmental
issues to be mitigated are likely to continue to arise. Terrestrial sand mining in particular tends to lead to protests
from citizens concerned with land use and environmental
issues, because it often results in highly visible, permanent
changes to the landscape. The western Great Lakes region
in the United States (Wisconsin, Minnesota), for example,
is the source of a large amount of sand being used for
fracking operations and is dealing with public protests
over the mining of these materials.
Bibliography
Finkl, C. W., and Hobbs, C. H., III, 2009. Mining sand on the continental shelf of the Atlantic and Gulf Coasts of the U.S. Marine
Georesources and Geotechnology, 27, 230–253.
Kosmatka, S. H., and Wilson, M. L., 2011. Design and Control of Concrete Mixtures, 15th edn. Skokie, IL: Portland Cement Association.
Meador, M. R., and Layher, A. O., 1998. Instream sand and gravel
mining: environmental issues and regulatory processes in the
United States. Fisheries, 23(11), 6–13.
Cross-references
Anthropogenic Impacts
Dredge and Fill
Dredging
Mass Physical Sediment Properties
SAND RIDGE
Marci M. Robinson
US Geological Survey, Eastern Geology and Paleoclimate
Science Center, Reston, VA, USA
Synonyms
Linear shoal; Sand shoal; Shoreface ridge; Tidal current
ridge
Definition
Sand ridges are elongate coastal or shelf sand bodies that
form bathymetric highs on the seafloor (Duane et al., 1972).
Description
Sand ridges are asymmetrical features composed of
unconsolidated fine to coarse sand and gravel. They are
typically 5-120 km long and 0.5-8 km wide, with heights
of more than 20 % of the water depth and slopes of less
than 1
. They occur on continental shelves in a wide range
of water depths, where sufficient sand exists and currents
are strong enough to transport sand-sized sediment. They
also usually occur in groups that are shore parallel, shore
oblique, or shore normal, with spacing between members
of $250 times the water depth, along topographically
irregular transgressive margins (Snedden and Dalrymple,
1999). Based on the relative progression of ridge
reworking and migration (Snedden and Dalrymple,
1999), sand ridges belong to one of three classes. Class
I ridges are young ridges that maintain their original
nucleus and are at or near their point of origination. Class
II ridges are partially evolved ridges that have maintained
some of their original nucleus and have migrated
a distance less than their original width. Class III ridges
are fully evolved forms that have maintained none of their
original nucleus. They have migrated a distance greater
than or equal to their original width.
Several hypotheses and models have been developed
that address the origin of sand ridges; these are largely
based on their distribution and orientation. They include
(1) the drowning of static, pre-transgressive features such
as barrier islands, beach ridges, and interfluves (e.g.,
Veatch and Smith, 1939); (2) the formation of posttransgressive features in equilibrium with the hydraulic
regime (e.g., Uchupi, 1968) or formed during storms
(e.g., Duane et al., 1972; Swift and Field, 1981); and
(3) the reworking of modern features associated with an
actively transgressing shoreline (e.g., Swift and Field,
1981; Robinson and McBride, 2008).
Bibliography
Duane, D. B., Field, M. E., Meisburger, E. P., Swift, D. J. P., and
Williams, S. J., 1972. Linear shoals on the Atlantic inner continental shelf, Florida to Long Island. In Swift, D. J. P., Duane,
D. B., and Pilkey, O. H. (eds.), Shelf Sediment Transport: Process
and Pattern. Stroudsburg: Dowden, Hutchinson, and Ross,
pp. 447–498.
Robinson, M. M., and McBride, R. A., 2008. Anatomy of
a shoreface sand ridge revisited using foraminifera: False Cape
Shoals, Virginia/North Carolina inner shelf. Continental Shelf
Research, 28, 2428–2441.
Snedden, J. W., and Dalrymple, R. W., 1999. Modern shelf sand
ridges: from historical perspective to a unified hydrodynamic
and evolutionary model. In Bergman, K. M., and Snedden,
J. W. (eds.), Isolated Shallow Marine Sand Bodies: Sequence
Stratigraphic Analysis and Sedimentologic Interpretation.
Tulsa, OK: SEPM, Special Publication 64, pp. 13–28.
536
SAND RIDGE