Puerto Princesa Underground River EarthCache

Welcome to the longest underground river in the world and one of the natural seven wonders of the world.

This formation comes to existenz, because of several reasons. One is the limestone or karst stone, which forms the area. It is common, that caves are in this kind of stone. Through a chain of chemical processes this stone could be dissolved by water, what leeds to empty spaces in the stone and of course caves.

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

Please recognize, that the informations and facts differ from source to source.

Emergence

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.

1. Water from the surface needs to get acidic, for example by picking up carbon dioxide from plant/tree roots. à H₂O + CO₂ → H₂CO₃
2. This acidic water needs to drain into a stone which has calcium in it, so most likely limestone à CaCO3^(s) + H2O(l) + CO(aq)2 → Ca(HCO3)(aq)2
3. Now, this solution needs to get into an open space, like a cave. But also mining shafts, tunnels, etc. are possible. Here the lower level of carbon dioxide in the air forces the bound carbon dioxide in the solution to get out of it. Left behind are the liquid water and the solid calcite. à Ca(HCO3)(aq)2 → CaCO(s)3 + H2O(l) + CO(aq)2

Factors of growing speed

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 in there)
• 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 1cm within 100years is an expected average, but it also could be more or even far less.

The cave is a habitat for a lot of different species and contains a rich biodiversity. So a large colony of bats lives permanently in the caves, as well as insects who adapted to this enviroment. The water also has a lot of live forms that are quiet endemic to the dark brackish water.

Please follow this procedure:

1. Read the Earthcache and the questions!
2. Go to the place and look for answers.
3. Send me the answers.
4. Afterwards you can immediatley log.

Please do it in this order. ;-)

1. The lime stone
   1. How is the limestone formation called? (Information board)
   2. How old in million years is it according to the audio guide (this differs from the information board)? (Audio Guide)
   3. Describe in your own words how, the underground river came to existence. (Information board + Listing)
2. Speleotherm formations
   1. How is the biggest speleotherm called? (Audio Guide)
   2. How old is it and how do determine this? (Listing + logical thinking)
   3. Could stalactites and stalagmites form under water, give an explanation for your answer? (logical thinking)
3. (Optional) Have fun and enjoy this amazing natural wonder! Pictures of your adventures are welcome!