Edinburgh Hill is a basalt cone on Livingston Island.... the remainder of an ancient volcano
The lava cools down in octagonal columns - a kind of organ pipe structure....
Similar structures can be seen close by: one of the nicest examples is "Der Grosse Parkstein", a basalt cone in Parkstein, a little village in northern Bavaria, Germany. Once it was carrying a medieval fortress, of which only a little church is left
The 4023 m Mount Erebus, first climbed by a party of six from Shackleton's Nimrod expedition in 1908, is still an active volcano. More might be hidden under the ice