| The view is northwest across scenic Copper Basin. Note the prominent outcrops of whitish tuffs of the upper Eocene Dead Horse Tuff lying below the more massive reddish-brown middle Miocene Jarbidge Rhyolite, dated by radiometric methods to 15.5 million years old. Local concentrations of beautifully preserved, carbonized 38 to 39-million-year-old leaf impressions occur within minor tuffaceous shale accumulations interbedded in the predominantly volcanic terrain. |