The two dominant art traditions of the Woodland Period were the art of the Adena Culture and the Hopewell. These cultures shared a number of visual motifs and symbols, and greatly influenced the art of other native North American cultures across the continent. Both the Adena and the Hopewell were known for building large scale earthworks as well as smaller pieces of sculpture and jewelry, often made from copper, or cut from mica, a layered silicate mineral. Because of the plundering of sites and an overall lack of documentation, a great deal remains unknown about the art traditions of the Adena and Hopewell.