hamilton period

from The Collaborative International Dictionary of English v.0.48

Hamilton period \Ham"il*ton pe"ri*od\ (h[a^]m"[i^]l*t[u^]n
   p[=e]"r[i^]*[u^]d). (Geol.)
   A subdivision of the Devonian system of America; -- so named
   from Hamilton, Madison Co., New York. It includes the
   Marcellus, Hamilton, and Genesee epochs or groups. See the
   Chart of {Geology}.
   [1913 Webster]