TYPES OF CAVES • Solution • Lava Tube • Sea • Glacier • Erosional
SOLUTION CAVES • caves most people are familiar with • formed as limestone is dissolved by acidic water • contain both stalactites and stalagmites
LAVA TUBE CAVES • found throughout the world in places where fluid lava has moved over the surface.
Most tubes form when fluid lava flows down the sides of volcanoes, the upper layer begins to cool, and the lava beneath continues to flow in tubular conduits beneath the surface. Due to the insulating effects of the hardened lava above, molten lava is able to travel a considerable distance underground with very little cooling.
Tubes may also form when lava follows trenches or gulleys on the surface, which then roof over as lava accumulates along the top edges.
SEA CAVES • Considered to be the most numerous type of cave • Formed by ocean waves attacking zones of weakness (“weak zones”) in coastal cliffs.
The cave may begin as a very narrow crack into which waves can penetrate and exert tremendous force, cracking the rock from within by both the weight of the water and by compression of air. Sand and rock carried by waves produce additional erosive power on the cave's walls.
GLACIAL (ICE) CAVES Form on glaciers, with surface crevasses channeling surface streams under-ground which melt a pathway through the ice.
EROSIONAL CAVES Erosional caves are those formed by the action of water or wind, carrying abrasive particles capable of carving rock. Erosional caves can be found in almost any kind of rock. Here water has carved out almost a mile of canyon passage with deep potholes.
Sandstone is soft and easily eroded. In some areas wind has sculpted large (but not deep or extensive) caves. Weathering in sandstone can be assisted by water dissolving the carbonate cement that holds the sandstone together.
A very common erosional type of cave that forms in soft rocks or clay is known as a soil pipe or claystone cave. Often found in arid regions, these caves form from the erosive power of water on soft rock.
CAVE FORMATIONS (SPELEOTHEMS) • Soda straws • Stalactites • Stalagmites • Flowstone • Shelfstone
Soda Straws Known as baby stalactites. Forms when water seeping into a limestone cave drips from the ceiling and leaves calcite forming thin, hollow tubes.
Stalactites Over time, water begins to flow along the outer edge of a soda straw, depositing calcite, making the icicle shape of a stalactite
Stalagmites Water dripping from the ceiling of a cave, or from a stalactite deposits calcite on the floor, creating a stalagmite from the ground up.
Flowstone Formed by calcite deposited by water running over rocks, other formations and down the walls of caves. It can be pure white or it can have a reddish brown color depending on the minerals present.
Shelfstone Shelfstone is flat-topped calcite that projects over the edge of a pool where it has grown into the pool. It can be very fragile and delicate or quite thick when the water has stayed in one place for a long time.
Credits and Resources http://www.caverntours.com/KIDSPAGE_Formations.html http://www.goodearthgraphics.com/virtcave/index.html http://www.weatherfriend.com/travel/txcave/txcavemain.html http://library.thinkquest.org/J002339/?tqskip1=1&tqtime=0613