Table 1: Comparative data on features discussed here.

FeatureStateSize (diameter in km)MagneticsGravityRecognized asAge

MansonIA38impactK
HaswellCO35lownegativeimpactPC
AmesOK14lownegativeimpactOrd
BeltonMO3solutionpost-Penn
EdgertonKS5lowimpactPC
MernaNE1wind erosionRecent
Big BasinKS1.3solutionPleisto
HavilandKS0.4impactRecent