Due to the efforts of the Alberta Federation of Rock Clubs, the Alberta Legislative Assembly officially recognized "petrified wood" as the official stone of Alberta in 1977. Commonly found in gravel pits all around Alberta, petrified wood is the result of the deposit of microcrystalline quartz in the pores and cells of the fallen trees of the Cretaceous and Paleocene times, some 60 to 90 million years ago.