One of four stone cairns (ND)

BISMARCK—The company building a controversial oil pipeline north of the Standing Rock Sioux Reservation failed to immediately notify state regulators after finding four stone cairns and other artifacts during construction in Morton County as tensions grew among pipeline opponents, documents show...

http://www.inforum.com/news/government/4149878-company-showed-lack-transparency-reporting-artifacts-discovery-days-leading