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 52 418 A MIDDLE EOCENE 158.5 177.5 NO AGE GIVEN NO AGE GIVEN 43 49 46 DSDP INITIAL REPORTS 52 418 A CENOMANIAN ALBIAN 272.5 282.0 NO AGE GIVEN NO AGE GIVEN NO AGE GIVEN 92 108 100 DSDP INITIAL REPORTS 52 418 A LOWER ALBIAN UPPER APTIAN 291.5 320.0 NO AGE GIVEN NO AGE GIVEN NO AGE GIVEN 106 112 109 DSDP INITIAL REPORTS 52 418 A LOWER APTIAN 320.0 320.2 NO AGE GIVEN NO AGE GIVEN 112 115 113.5 DSDP INITIAL REPORTS