pk minds

Singing sand, also called whistling sand or barking sand, is sand that produces sound. The sound emission may be caused by wind passing over dunes or by walking on the sand. Certain conditions have to come together to create singing sand: The sand grains have to be round and between 0.1 and 0.5 mm in diameter. The sand has to contain silica. The sand needs to be at a certain humidity. The most common frequency emitted seems to be close to 450 Hz. There are various theories about the singing sand mechanism. It has been proposed that the sound frequency is controlled by the shear rate. Others have suggested that the frequency of vibration is related to the thickness of the dry surface layer of sand. The sound waves bounce back and forth between the surface of the dune and the surface of the moist layer, creating a resonance that increases the sound's volume. The noise may be generated by friction between the grains or by the compression of air between them. Other sounds...

Have you heard of Haskell free library? I felt this amazing. The library has some parts of 'The Worlds Longest Border' running inside... This border that runs between two extremely powerful nations that has great relations between each other has much more interesting stories to say. It runs between the runways, libraries, forests and public places. How'd it be when two flights from different nations runs parallel reaching different destinations? Entered from US must exit to US. Entered from Canada must Exit to Canada. Guard force will be taking action otherwise. If you are IN from Canada  and OUT to US by mistake report soon to the "walking area"... Americans sit on the right chair but Canadians sit on the left chair ! :) That table has an amazing fate. What if a Canadian is pulling the table to their side when US people are sitting in those chairs ? :) Interesting !