In geology, a blowhole or marine geyser is formed as sea caves grow landwards and upwards into vertical shafts and expose themselves towards the surface, which can result in hydraulic compression of sea water that is released through a port from the top of the blowhole.The geometry of the cave and blowhole along with tide levels and swell conditions determine the height of the spray.
Jagged limestone formations, some as tall as two meters (six feet), have formed the caves in the cliffs along the southern coast of Christmas Island. Incoming waves flood the caves, pushing a blustering spout of water and air up through the formations. The blowholes in the caves' ceilings create spectacular plumes that fly up into the atmosphere with a loud, distinctive gushing sound, before crashing onto the limestone rocks.
To log this earthcache you need to answer the following questions:
- On the day of you visit measure the time between two sprays
- Observe and describe the sea on that day (calm, rough, etc)
- If you now combine the information of Q1 and Q2 how do both related to each other and the blowhole here?
- What do you think, which forces have shaped these crazy sculptures in the karst limestone pinnacles?
- Taking Q4 and your observations from Q1-Q3 what do you think the spray would be like in a few years if the conditions are exactly as today?
- Attach a picture of yourself or your GPS in front of the blowholes to your find log.
You can log your find immediately but please send the answers to me via profile email or GC Messenger within about ten days, or the find log may be deleted.
Hope you enjoy the nice and newly build boardwalk here and the magnificent view.