Biserujka cave
An undistinguished stone house in the middle of a bare karst
landscape hides the entrance to a cave 12 m under the surface.
Although it is not very long if compared to other caves, only 110 m
deep, the Biserujka cave has everything that is characteristic of
karst phenomena. It has lots of typical features such as
stalactites and stalagmites, and also a gallery or hall, which is
suitable for the holding of concerts.
Stalactites are formed by the deposition of calcium carbonate
and other minerals, which is precipitated from mineralized water
solutions. Limestone is calcium carbonate rock which is dissolved
by water that contains carbon dioxide, forming a calcium
bicarbonate solution. The chemical formula for this reaction
is:
CaCO3(s) + H2O(l) + CO2(aq) ?
Ca(HCO3)2(aq)
This solution travels through the rock until it reaches an edge
and if this is on the roof of a cave it will drip down. When the
solution comes into contact with air the chemical reaction that
created it is reversed and particles of calcium carbonate are
deposited. The reversed reaction is:
Ca(HCO3)2(aq) ? CaCO3(s) + H2O(l) +
CO2(aq)
An average growth rate is 0.13 mm (0.005 inches) a year. The
quickest growing stalactites are those formed by fast-flowing water
rich in calcium carbonate and carbon dioxide, these can grow at 3
mm (0.12 inches) per year.
Every stalactite begins with a single mineral-laden drop of
water. When the drop falls, it leaves behind the thinnest ring of
calcite. Each subsequent drop that forms and falls deposits another
calcite ring. Eventually, these rings form a very narrow (0.5 mm),
hollow tube commonly known as a "soda straw" stalactite. Soda
straws can grow quite long, but are very fragile. If they become
plugged by debris, water begins flowing over the outside,
depositing more calcite and creating the more familiar cone-shaped
stalactite. The same water drops that fall from the tip of a
stalactite deposit more calcite on the floor below, eventually
resulting in a rounded or cone-shaped stalagmite. Unlike
stalactites, stalagmites never start out as hollow "soda straws."
Given enough time, these formations can meet and fuse to create
columns
referenz
by wikipedia
Log permission
First log your visit and then send me the answers per
email. Please do not write the answers into your
log!
- Photo with you in front of the house or inside the caves.
(optional)
- In this cave you got stalactites and stalagmites, which ones
are growing upwards?
- Whats the name of the last room in the cave?
- Whats the average temperature in the cave?
Images
