Page 476 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

440 part III The earth–Atmosphere Interface
Collapsed sinkhole
Collapse blocks
Drip stones
Drip curtain
Column
Disappearing river
Waterfall
Collapse blocks
Surface stream
Soluble rock (limestone) Stalactite
Sinkhole
(a)
Chamber
Cave pool
(c) Near column
Stalagmite Underground stream
(b) Dripstone drapery
(d) Flowstone and pool
(e) Soda straws
▲Figure 14.22 An underground cavern and related forms in limestone. A column is created when stalactites from the ceiling and stalagmites from the floor connect. All cave photos from Marengo Caves, Marengo, Indiana. [All photos by Bobbé Christopherson.]
including algae, small invertebrates, amphibians, and fish. Biospeleology is the study of cave organisms.
In a cave discovered in 1986, near Movile in south- eastern Romania, cave-adapted invertebrates were dis- covered after millions of years of sunless isolation. Thirty-one of these organisms were previously unknown. Without sunlight, the ecosystem in Movile is sustained by sulfur-metabolizing bacteria that synthesize organic matter using energy from oxidation processes. These chemosynthetic bacteria feed other bacteria and fungi that, in turn, support cave animals. The sulfur bacteria
produce sulfuric acid compounds that may prove to be important in the chemical weathering of some caves.
Mass-Movement Processes
In the South American country of Colombia, Nevado del Ruiz is the northernmost of two dozen dormant (not ex- tinct, sometimes active) volcanic peaks in the Cordillera Central. This volcano erupted six times during the past 3000 years, killing 1000 people during its last eruption,