Fission track age for apatite sample MS_004_42c from the western Greater Cauc...

Each graticule square has an area of 0.000001386 cm2. Number of graticule squares is used with the track count to determine track densities.每个格网方格（graticule square）的面积为0.000001386平方厘米。可结合格网方格总数与磁道数计算得到磁道密度。