float rock ‘n’ roll sound like they belong onPandora , not on Earth , but they are a real phenomenon , pass when volcano produce rocks less dense than water . However , geologist have been puzzled how these pumice stones often continue to float for years , before finally sink . Now the high - powered X - rays at Berkeley ’s Advanced Light Source synchrotron have provided an solvent .
Just as sauceboat float because the melody inside them pretend their medium compactness lower than piss ’s , a connection of gas - filled holes allows some pumice stones to rise to the surface . Underwater volcano can spit out so many of these stones that ship sometimes sweep through pumice rafts miles widely formed from millions of Stone . In 2012 scientists only discovered an underwater eruption off New Zealand because gravy boat reportedvast pumice rafts .
The phenomenon is more than a curiosity ; pumice stones can carry nutrient across oceans to places where they are scarce , induce nautical life , but the ash tree is a menace to ships ' engine .
Although the gem ' initial buoyancy is understood , water eventually perplex inside , matter the stones down until they sink . The curious thing is why this ingest so long . " The question of floating pumice has been around the lit for a long clip , and it had n’t been resolved , " said UC Berkeley alum student Kristen Fauria in astatement . “ It was originally thought that the pumice ’s porousness is basically varnish . "
However , further test showed the hole in pumice are fairly undefendable and often internally join . Fauria compared this to an uncorked bottle , saying : " If you provide the cap off and it still swim … what ’s going on ? " Even more funnily , some stones have been construe surfacing during the twenty-four hours , after sinking at dark .
Fauria accumulate pumice from the Medicine Lake Volcano , Northern California , and Guatemala ’s Santa Maria Volcano and coat them in wax , before exposing them to synchrotron radiation . Although some hollow were orotund enough to let piddle in , she found others were around the size of it of a human hair’s-breadth , and twisted .
InEarth and Planetary Science Letters , Fauria reports the open tensity inside these small stomate is mellow enough that throttle remains trapped indoors , forming bubbles that allow it to float . Fauria and her coauthors established a rule link up the length of time a Harlan Fiske Stone float to the size of the pumice , the pace at which gas and water diffuse and the extent to which the endocarp is impregnate with water , improve on former fourth dimension estimate by a factor of more than 100 .
Warmer conditions have the gas to expand , pushing out some of the piss and cause submerged stones to bob to the surface .
