Radiocarbon dating, microscopy of paleobotanical samples, and analytical pyrolysis of fluvial sediments in Arlington Canyon on Santa Rosa Island by another group found no evidence of lonsdaleite or impact-induced fires. Research published in 2012 has shown that the so-called "black mats" are easily explained by typical earth processes in wetland environments.
Research conducted at Arlington Canyon on Santa Rosa Island, involving radiocarbon dating, microscopic examination of ancient plant remains, and thermal analysis of riverbank deposits by another group found no indication of lonsdaleite or fire-related damage. Subsequent studies published in 2012 explained the "black mats" as a result of natural processes occurring in wetland ecosystems.