Excerpts from the Wikipedia entry:
A hoodoo is a tall, thin spire of rock that protrudes from the bottom of an arid drainage basin or badland. Hoodoos typically consist of relatively soft rock topped by harder, less easily eroded stone that protects each column from the elements.Etymology of the English word uncertain - probably corruption of voodoo, implying magical cause.
Hoodoos (peribacası) are also found in the Cappadocia region of Turkey, where houses have been carved into the formations. The hoodoos were depicted on the reverse of the Turkish 50 new lira banknote of 2005–2009. In French, the formations are called demoiselles coiffées (ladies with hairdos) or cheminées de fées (fairy chimneys).