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Science beats hoaxes

A cache by tulak Send Message to Owner Message this owner
Hidden : 08/18/2010
3.5 out of 5
1.5 out of 5

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Geocache Description:

This earthcache is trying to show how, sometimes, our senses may confuse us, how the otherwise splendid "common sense" may take us on the wrong path.

Science over common sense (well, sometimes)

The Earth sciences teach us to find more facts about our planet and to discover the tools and ways how to look for and at them. The amazing inventions and excellent ideas brought to us instruments scientifically measuring and evaluating Earth processes, shapes and interactions. The instruments - if used properly - are much better than our own senses. This earthcache is trying to show how, sometimes, our senses may confuse us, how the otherwise splendid "common sense" may take us on the wrong path.

Magnetic hills as optical illusions

All over the world, there are many places where the Earth (usually a road) shape creates an optical illusion which is usually called "magnetic hill" (also "gravity hill" or "electric brae" or even "mystery hill"). Such "hill" is a place "...where the layout of the surrounding land produces the optical illusion that a very slight downhill slope appears to be an uphill slope..." ( There are plenty Internet sites showing examples, photos and explanations (sometimes scientific explanations, sometimes less scientific "explanations"). One of the lists of magnetic hills is maintained at (however, some of the "hills" listed there are not the Earth hills but touristic attractions artificially created for commercial exploration). The optical illusion is usually created by a stretch of road in a hilly area where the level horizon is obscured. Objects such as trees and walls which normally provide visual clues to the true vertical, may be leaning slightly (

What to look for

This earthcache brings you to such place in Philippines, not far from Manila, but still not that easy reachable (you may need to take several jeepneys unless you drive your own car). The place has also its own web site ( - which does not tell much but may be inspiring for one of your tasks (described below). It is located on a side-road on the slopes of the Mt Makiling National Park - but it is still a road so take precautions when exploring the place. This is the place:

How to claim the cache

  1. Make your own photo of the road, preferably with you or your GPS. Or a photo that is properly geotagged.
  2. Try to use your GPS at both ends of the "magnetic hill". Is the difference in elevation large enough to be observable by the usual outdoor GPS? If yes, what difference have you measured?
  3. What are the instruments or methods for measuring the slope grade (this activity is a part of a more general term "surveying").
  4. [Optionally] Try a method, right on the spot, to prove that the "magnetic hill" is rather an illusion. Photos welcome.
Please email me the answers for 2 and 3, and log images for 1 and 4.

Once you are there...

...I recommend to visit also the "Scout camp" Scout monument and to drive to the "National Arts Center" (nice views, usually open only on weekdays until 16:00). National Arts Center You are also very close to the IRRI (International Rice Research Institute) where is located a very nice and rich "Rice museum" (open to public in working hours). In the vicinity (but a bit of hiking is needed), there is also another cache worth to visit - "Sulphur from mother earth" (GC19DJ4) (visited so far only once by me two year ago).

Additional Hints (No hints available.)

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