 Absolute dates, subject to a statistical uncertainty, are determined through radiometric dating using isotope ratios such as 40Ar/39Ar dating, which can be used to identify the date of solidifying basalt.In the CRBG deposits 40Ar, which is produced by 40K decay, only accumulates after the melt solidifies.Other flood basalts include the Deccan Traps (late Cretaceous period), that cover an area of 500,000 km2 (200,000 sq mi) in west-central India; the Emeishan Traps (Permian), which cover more than 250,000 square kilometers in southwestern China; and Siberian Traps (late Permian) that cover (800,000 sq mi) in Russia.