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Tree rings preserve evidence of three
distinct episodes of hydrologic change within
the wetland during the past century, at a
location where no previous effects of salt
mining had been reported. This study is one
example of the U.S. Geological Survey's use
of tree rings to investigate hydrologic
conditions during both the past and present.
For more information regarding additional
tree-ring studies, please contact a Survey
representative from one of the two addresses
listed below.
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Figure 4.Solution-salt mining
The solution mining ofsaltin the late 19th
century began with drilling a hole down to the salt
layer, and the installation of two steelcasingsinto
the hole.Fresh waterwas pumped down the
inside casing where the waterdissolved the rock
salt and produced a brine (salt water).The brine
was "lifted" and laterpumped up to land surface in
the outside casing.Aslarge amounts ofrock salt
were dissolved, the unsupported shale rock above
the saltcavity began to break and fall into the salt
cavern.As the cavern became larger, the shale
bedrockcontinued to breakand slowly fillthe
cavern with broken rock, which eventually caused
subsidence atland surface.Initially,the
subsidence was smalland gradual,and generally
unnoticed.Later, asthe cavities became larger,
the land-surface subsidence was greaterand
more noticeable.
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Kappel, W.M., Sherwood, D.A., and Johnston,
W.H., 1996, Hydrogeology of the Tully
Valley and characterization of mudboil
activity, Onondaga County, New York:
U.S. Geological Survey Water-Resources
Investigations Report 96-4043, 71 p.
Phipps, R.L., 1985, Collecting, preparing,
crossdating, and measuring tree increment
cores: U.S. Geological Survey Water-
Resources Investigations Report 85-4148,
48 p.
Yanosky, T.M., and Kappel, W.M., 1997,
Effects of solution mining of salt on
wetland hydrology as inferred from tree
rings: Water Resources Research, v. 33,
p. 457-470.
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