leg site hole age mnemonic auxiliary age mnemonic top of section depth(m) bottom of section depth(m) special condition age auxiliary age averaged age age top of section(million years) age bottom of section(million years) average age(million years)t data source 20 198 A UPPER CRETACEOUS 90.5 109.5 MISSING HOLE OR DRILLED INTERVAL NO AGE GIVEN NO AGE GIVEN 65 100 82.5 DSDP INITIAL REPORTS 20 198 A CAMPANIAN SANTONIAN 109.5 119.0 NO AGE GIVEN NO AGE GIVEN NO AGE GIVEN 70 82 76 DSDP INITIAL REPORTS 20 198 A LOWER CAMPANIAN 119.0 134.5 A LEGITIMATE AGE INVERSION NO AGE GIVEN NO AGE GIVEN 74 78 76 DSDP INITIAL REPORTS