NATURAL WONDERS
… as a result of groundwater
Hot Springs, Geysers and
Fumaroles
Hot Springs, Geysers and
Fumaroles
• At a depth of about 20m, the temperature
remains constant all year, and the water of a well
or spring is close to the same
• Below 20m, heat from the earth’s interior raises
the temp. about 1°C for every 40m.
• As a result, water from deep artesian wells or
springs can be much warmer
• Groundwater may also be warm in regions of
recent volcanic activity, as the igneous rock is
still hot enough to boil water
Hot Springs, Geysers and
Fumaroles
Hot Springs occur where heated water
comes to the surface
If hot water comes up through thick, sticky
clays, a sputtering spring called a paint
pot results (also called a mud volcano)
Geysers are boiling hot springs that
periodically erupt and gush hot water and
steam (eg. Old Faithful in Yellowstone
National Park)
Hot Springs
Paint Pot
Hot Springs, Geysers and
Fumaroles
Geysers tend to have constricted tubes, so
the water at the bottom is under pressure,
and once it develops steam, it forces
superheated water up to the surface
Fumaroles are fissures in the ground where
steam and hot gases escape, generally
found in volcanic regions, which can be
good sources of geothermal energy
Geyser cross section
Old Faithful
(geyser)
MINERALS IN GROUNDWATER
• Rain has few dissolved minerals
• As water seeps into the ground, it passes through soil
layers and dissolves minerals in the soil and bedrock
The kind and amount of minerals in groundwater depends
on:
1. kind of rock through which water passes
2. the distance it travels underground
3. the water temperature
Water Hardness
Hard water contains a substantial amount of
dissolved minerals (ions), usually calcium,
magnesium or iron.
• Water hardness interferes with its uses, for
example it will not form soap suds well and
forms scale in water pipes etc.
• Hard water occurs in areas that have
limestone bedrock, due to dissolved
calcium (from calcite)
Mineral Springs
• Sometimes a spring contains so much
dissolved mineral matter that it cannot be
used for ordinary drinking or washing
• This is called a mineral spring
(sometimes these are used as health
resorts/spas)
• Water from hot springs usually has a high
mineral content because hot water
dissolves minerals better than cold
Caverns
• As groundwater flows through
limestone, the carbonic acid it
contains slowly dissolves the
limestone
• After thousands of years, the
cracks between layers (or
fissures that run down from the
surface) become so large that
they form networks of
underground tunnels called
caverns (or caves)
Mineral Deposits
• Where groundwater
drips from the roof of
a limestone cave, it
slowly deposits calcite
• These slender
deposits, shaped like
icicles, are called
stalactites
Mineral Deposits
• On the floor beneath
the stalactites are
blunt, rounded
masses called
stalagmites
• Where stalactites and
stalagmites meet,
pillars are formed
Other Mineral Deposits
• Travertine are calcite
deposits around mineral
springs
• Geyserite is silica
deposited around geysers
• Petrified wood is formed
when minerals dissolved
in groundwater replace
the decaying wood of
buried trees, and
reproduces the wood
structure
Do Chapter 9 Review
p.166-167 #1-15 (MC)
(write out the question and select
the best answer!)