The Chocolate Hills are an unique geological formation in Bohol region, Philippines. There are 1,776 hills spread over an area of more than 50 square kilometres. They are covered in green grass that turns brown during the dry season, hence the name. The most tolerable geological theory of the Chocolate Hills of Bohol is that the hills were the result of centuries of weathering of marine limestone. The National Committee on Geological Sciences declared the Chocolate Hills of Bohol a National Geological Monument on June 18, 1988, in recognition of its amazing characteristics.