The Volcano and the rocks it creates, are just one of many things that interest people. For example, obsidian is just one of many rocks that are formed cause of the volcano which are either created from molten magma that quickly cools and hardens making an almost glass type feature to the rock or something more complicated.
Yes, i know what you are thinking, YOU CANT STAND IN THE CLOUDS?! Blah,Blah Why you ask? well thats simple...CAUSE I FELT LIKE IT. Speaking of clouds, clouds are made up of mostly water vapor and other gases.
rivers help in the making of many rocks because of current and other aspects which slowly erode the rocks making them gradually become smaller, making sand and sedimentary rock as a result.