== thorium by terrain (area-weighted median ppm, share of area) ==
contact  opening  median 4.90  area share 0.186
contact  plain    median 5.48  area share 0.438
contact  highland median 5.49  area share 0.376
outside  opening  median 2.14  area share 0.037
outside  plain    median 2.58  area share 0.027
outside  highland median 1.48  area share 0.936
share of the Moon's Th excess >3 ppm on opening: 0.137
share of the Moon's Th excess >3 ppm on plain: 0.441
share of the Moon's Th excess >3 ppm on highland: 0.422
in the contact: {'opening': np.float64(0.137), 'plain': np.float64(0.431), 'highland': np.float64(0.382)}

== each mare floor against its land 0-150 km ==
                   mare  status    zone  th_mare  th_land_0_150  mare_minus_land
          Mare Australe opening  beyond     1.74           1.64             0.10
South Pole Aitken Basin opening  beyond     2.78           2.45             0.33
           Mare Smythii opening  beyond     2.14           1.88             0.26
       Mare Moscoviense opening  beyond     1.81           1.23             0.58
                 Apollo opening  beyond     1.95           2.12            -0.17
           Mare Imbrium opening contact     5.71           7.60            -1.89
       Mare Serenitatis opening contact     2.84           4.03            -1.19
           Lacus Mortis opening contact     3.20           3.31            -0.11
      Mare Fecunditatis opening    hill     2.45           2.17             0.28
           Mare Crisium opening    hill     1.95           1.81             0.14
           Mare Humorum opening    hill     2.99           2.76             0.23
          Mare Nectaris opening    hill     2.43           2.31             0.12
         Mare Orientale opening    hill     1.43           1.26             0.17
     Mare Humboldtianum opening    hill     1.78           1.70             0.08
          Mare Marginis   plain  beyond     2.09           1.76             0.33
           Mare Ingenii   plain  beyond     2.62           2.97            -0.35
    Oceanus Procellarum   plain contact     5.10           4.37             0.73
         Mare Insularum   plain contact     8.94           8.11             0.83
          Mare Frigoris   plain contact     5.28           5.96            -0.68
            Mare Nubium   plain contact     5.56           3.65             1.91
       Lacus Somniorium   plain contact     3.00           2.97             0.03
          Mare Cognitum   plain contact     6.38           8.49            -2.11
           Mare Vaporum   plain contact     5.00           5.07            -0.07
          Cognitum East   plain contact     8.19           7.67             0.52
   Mare Tranquillitatis   plain    hill     2.67           2.60             0.07
         Lacus Temporis   plain    hill     2.40           2.37             0.03
      Palus Epidemiarum   plain    hill     2.75           2.52             0.23
           Mare Undarum   plain    hill     1.72           1.75            -0.03

opening: n=14  Th vs FeO rho=+0.49  Th vs TiO2 +0.15  Th vs area +0.40  Th vs gravity -0.41
                         Th_ppm  FeO_wt  TiO2_wt       area
name                                                       
Mare Imbrium               5.56   16.50     3.58  872806.29
Lacus Mortis               3.21   12.02     0.75   33638.02
Mare Humorum               3.00   16.56     4.01  109128.60
Mare Serenitatis           2.86   16.59     2.98  310675.57
South Pole Aitken Basin    2.79   14.31     1.17   56574.94
Mare Nectaris              2.50   13.45     2.35   68147.34
Mare Fecunditatis          2.47   15.43     3.41  328368.92
Mare Smythii               2.15   15.99     3.51   41523.41
Mare Crisium               2.00   15.30     3.12  180925.01
Apollo                     1.99   16.42     4.10   21590.17
Mare Moscoviense           1.81   15.48     3.05   23084.05
Mare Humboldtianum         1.73   10.32     0.81   29489.93
Mare Australe              1.73   11.03     1.28  224236.92
Mare Orientale             1.48   12.62     2.66   51068.87

plain: n=14  Th vs FeO rho=+0.50  Th vs TiO2 +0.26  Th vs area +0.57  Th vs gravity +0.43
                      Th_ppm  FeO_wt  TiO2_wt        area
name                                                     
Mare Insularum          9.40   14.92     3.29   420509.23
Cognitum East           8.22   16.22     3.90    58518.49
Mare Cognitum           6.42   16.72     4.10    72032.88
Mare Nubium             5.74   15.79     3.90   217248.48
Mare Frigoris           5.32   14.31     0.77   263195.83
Oceanus Procellarum     5.13   17.28     5.25  1784148.11
Mare Vaporum            4.95   16.04     4.61    64858.52
Lacus Somniorium        3.03   12.51     1.04    77863.42
Palus Epidemiarum       2.74   13.67     4.12    29294.75
Mare Tranquillitatis    2.66   17.28     8.27   394061.48
Mare Ingenii            2.63   14.77     1.70    32643.27
Lacus Temporis          2.37    9.48     0.58    33035.32
Mare Marginis           2.01   14.12     2.58    64370.89
Mare Undarum            1.75   14.18     2.49    23962.10
