A

anomalies    Unusually high or low values or patterns.

aquifer (surficial and confined)    A permeable water-bearing layer of sediment or rock; a confined aquifer is isolated from the ground surface by one or more low-permeability layers of sediment or rock, while a surficial or unconfined aquifer is not.

B

brackish    Slightly to moderately salty.

C

conductivity    The ability of a material or mixture to carry an electrical current.

D

dipole    A pair of positive and negative charges separated by a small distance.

E

embayment    A bay or baylike shape; the formation of a bay.

estuary    A body of water typically found where a river meets the ocean.

G

glacial till    An unstratified, unconsolidated mass of boulder, pebbles, sand, and mud deposited by the movement or melting of a glacier.

groundwater    Water located beneath the ground surface or sediment surface in pore spaces and fractures.

I

interpolated    Interpreted conditions between locations of measured data.

intertidal    Of or relating to the zone of the shore between the high-water mark and low-water mark.

inversion    The process of working backwards from measured properties, such as electrical resistivity, to reconstruct the actual conditions that yielded the measurements.

J

Julian day    Day of the year measured from January 1, without regard to months.

L

linearized    Converted from an irregular or curved path into a straight line to simplify computations.

M

moraine    An accumulation of boulders, stone, or other debris carried and deposited by a glacier, often in the form of a ridge.

N

nutrients    Chemicals that organisms need to live and grow, especially dissolved forms of nitrogen in the case of estuaries.

P

piezometer    Small-diameter pipe or tube with a short perforated interval near the end which is inserted into the ground to measure pressure or "head" at a specific depth within an aquifer; groundwater samples can also be collected from such a device.

potential    See voltage potential.

profile    A cross section produced from geophysical data.

pseudosection     An image plotting apparent electrical resistivity data against position along a traverse line; this image is produced as an intermediate step to reconstructing the true electrical properties and geometry of a measured transect.

R

resistivity    A measure of how strongly a material or mixture opposes the flow of electric current.

S

saline    At or near the saltiness of seawater.

seepage meter    An instrument that measures local groundwater discharge or inflow at the sediment-water interface.

shapefile    A data format commonly used for geographic information systems files.

streamer    A cable towed behind a ship that contains electrodes or acoustic sensors.

subtidal    The marine zone below low tide that is always covered by water.

surface water    Water occurring in the form of a stream, river, lake, estuary, or ocean.

T

trackline    An individual segment of a larger marine geophysical survey, often assigned a sequential number that corresponds to the order in which that interval of data was collected.

V

varved clay    An accumulation in proglacial lakes of yearly couplets of lacustrine beds: during the summer, silt settles and accumulates and in the winter clay-sized material settles and accumulates. The alternating layers usually display contrasting colors.

voltage    The driving force that moves an electrical current between two points, measured in units of volts.

voltage potential   The property of electrical potential energy divided by electrical charge, usually measured in volts.