Task
To log the cache, send me the answers to the following question.
1. Reference point 1 (information board): How ist the limestone formation called and how old is it?
2. In the cave: What is the biggest speleotherms name and how old is it if taking the growth rate in the listing?
3. In your own words, how came the cave to existence and could stalactites and stalagmites form under water?
Picture is necessary and should show that you have been in the area. With at least your geocaching name or yourself in the picture.
The Puerto Princesa Underground River, located in the Palawan province of the Philippines. It is the longest underground river in the world and one of the natural seven wonders of the world.
Geology and Formation
The Puerto Princesa Underground River flows through a complex network of caves within the karst stone. This geological marvel began to form millions of years ago, through a combination of geological processes including erosion, tectonic activity, and the dissolution of limestone.
Limestone Formation: The region's limestone bedrock is primarily made up of calcium carbonate, which is susceptible to dissolution by acidic water. Over time, rainwater, containing carbon dioxide absorbed from the atmosphere, percolated through the limestone, creating fractures and cavities in the rock.
Karst Topography: The unique karst topography of the area, characterized by limestone formations, played a crucial role in the development of the underground river system. As the limestone dissolved, extensive cave networks, sinkholes, and underground rivers formed.
Some facts:
- Length of the river: 8.2km
- Navigable: 4.5km
- Navigable for tourists: 1.2km
- Tidal influence: 6km into the cave from the entrance
- Size of chambers: up to 120m wide and 60m high
Speleotherms
Speleothems are secondary mineral deposits of mostly calcite which form on ceilings, walls or floors of caves. The existence of speleothems is due to a chemical process, which needs a certain geology.
- Water from the surface needs to get acidic, for example by picking up carbon dioxide from plant/tree roots. H2O + CO2 → H2CO3
- This acidic water needs to drain into a stone which has calcium in it, so most likely limestone CaCO3(s) + H2O(l) + CO(aq)2 → Ca(HCO3)(aq)2
- As soon as this solution reaches into an open space, like a cave, it reacts with the air. After the reaction liquid water and solid calcite are left. Ca(HCO3)(aq)2 → CaCO(s)3 + H2O(l) + CO(aq)2
The speed of growing differs. That means, in one and the same cave speleothems grow with different speed. Even further, the growth of a single speleothem might differ over time. Factors are:
- Acidity of the water (how much carbon dioxide is carried)
- Calcite concentration in the water (how much calcite can get into the solution)
- Amount of water coming through
- Temperature in the open space
- Composition of air (how high is the carbon dioxide level)
In general, a growth of 1 cm within 100 years is an expected average, but it also could be more or even far less.