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Warm spring locations and geological characteristics
The warm springs of Ireland are generally located in two clusters,
one occurring in Leinster , the other in Munster . The Leinster springs
tend to occur along the Meath - Kildare border. The Munster springs are
generally slightly more dispersed. All warm springs in Ireland issue
from the same bedrock (Dinantian Limestone) which occurs between the
granite, metamorphic and Silurian rock of the Leinster Caledonian
granite massif on the southeast and the Ordovician - Silurian Balbriggan
and Louth blocks to its north (Aldwell and Burdon, 1980). Some small
Tertiary intrusions have been reported from the vicinity of warm springs
and their occurrences can often be located with respect to fold
structures (Minerex, 1983).
Hydrological Characteristics
Systematic gauging of the yields of all Irish warm springs has not been
undertaken to date. It is certain however, that most if not all would
show a strong seasonal variation in discharge as has been shown in the
springs that have been subject to examination (St. Gorman’s,
Kilbrook). Maximum flows will occur in spring and summer while many will
go dry or have minimal discharge in the autumn and winter, thus
following a normal regime for groundwater (Aldwell and Burdon,
1980).
Thermal Characteristics
Water temperature in Irish thermal springs has generally been recorded
between approximately 12.5 and 22oC. Temperature data recorded over a
nine year period during the 1980’s at St. Gorman’s spring revealed a
close relationship with discharge. Generally, as flow increased,
so too did temperature and as discharge decreased the temperature did
the same. This indicates that the source of heat is greater than
the amount of heat disipated by water and that the larger the volume of
water moving underground the more it is brought into contact with warm
rock and higher temperatures (Aldwell and Burdon, 1980). At St
Gormans the temperature generally peaked in spring and declined from May
to October (Minerex, 1983). Physico-chemical characteristics of warm
spring water
In general, the ionic content of warm spring water is typical of Irish
groundwaters (Minerex, 1983). Total dissolved solids concentrations tend
to range from 280 to 480 ppm – expected for groundwater issuing from
limestone aquifers (Aldwell and Burdon, 1980). The main chemical
composition of Irish warm spring water is not however related to water
temperature. High chlorine and total dissolved solids are
restricted to three springs ( Louisa Bridge, St. Patrick’s Well
Celbridge and St. Bridget’s Well) which occur along a synclinal
structure (Minerex, 1983). This is reflected in elevated conductivities
at these sites.
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