[けい, kei] (n, n-suf) (1) system; lineage; group; (2) { math } corollary; (3) (geological) system (range of strata that correspond to a particular time period); (4) (taxonomical) series; (P) #222
[せい, sei] (ctr) (1) counter for generations; (n, n-suf) (2) (geological) epoch #318
[き, ki] (n, n-suf) (1) period; time; (2) (geological) age #341
[だい, dai] (n, n-suf) (1) charge; cost; price; (2) (See 台・だい・6) generation; age; reign; (3) (geological) era; (4) (after someone's name or title) a representative of; on behalf of; for (someone); (5) (See 代表電話番号) used after a phone number to indicate that it is a switchboard number; (ctr) (6) (See 台・だい・6) counter for decades of ages, eras, etc.; (7) counter for generations (of inheritors to a throne, etc.); (8) (abbr) (See 代理申請会社) proxy application company #376
[けいとう, keitou] (n) system; family line; geological formation; lineage; ancestry; (P) #1225
[き, ki] (n) (1) (abbr) (geological) period; (2) (abbr) (See 日本書紀) Nihon-shoki #2296
[ちしつ, chishitsu] (n) geological features; (P) #5367
[ちそう, chisou] (n) stratum; geological formation; layer; bed (coal, gravel, etc.); (P) #17295
[けいどう, keidou] (n, vs) tilting (of a geological block)
[ちしつこうぞう, chishitsukouzou] (n) geological structure