FLORIDA GEOLOGICAL SURVEY


 GLOSSARY

aquifer an underground geological formation that stores water; aquifers are the source of
spring water and well water.

chert limestone replaced by quartz (silica). Used by Native Americans for variety of imple-
ments including knives and projectile points. Also known as flint.

first magnitude spring a spring with a flow rate of 100 cubic feet per second (64.6 mil-
lion gallons per day) or more.

groundwater level the measurement, in feet, of the elevation of the top of an aquifer, as
measured in a network of groundwater monitoring wells and/or supply wells. The level can
fluctuate in response to aquifer recharge and groundwater withdrawals.

Hydrilla an invasive, exotic, aquatic plant that is growing rampant in many springs and
rivers.

hydrogeology the study of subsurface waters in their geologic context.

impermeable not permitting the passage of fluids. In the case of geologic formations, an
impermeable layer of earth is one through which groundwater cannot pass.

karst a limestone region with underground drainage and many cavities and passages
caused by the dissolution of the rock.

sinkhole a hole at the earth's surface that is formed when an underlying limestone cavi-
ty collapses.

spring recharge basin -the "area of contribution" for a spring's supply of groundwater.
Spring recharge basins encompass land areas that contribute surface water and rainwater
to the spring flow. The boundaries of this three-dimensional area are determined from
hydrologic studies of the groundwater flow, which can then be delineated on the land sur-
face. Within the spring recharge basin, large volumes of groundwater are contained within
microscopic spaces in the limestone; however, groundwater movement is generally domi-
nated by the flow of water through water filled conduits and fractures in the limestone
aquifer.

spring run a spring-fed stream.