NATURAL WONDERS … as a result of groundwater

1. NATURAL WONDERS … as a result of groundwater

2. Hot Springs, Geysers and Fumaroles

3. 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

4. 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)

5. Hot Springs Paint Pot

6. 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

7. Geyser cross section Old Faithful (geyser)

8. 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

9. 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)

10. 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

11. 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)

12. 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

13. Mineral Deposits • On the floor beneath the stalactites are blunt, rounded masses called stalagmites • Where stalactites and stalagmites meet, pillars are formed

14. 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

15. Do Chapter 9 Reviewp.166-167 #1-15 (MC) (write out the question and select the best answer!)