The Sitka Graywacke is an Upper Cretaceous to Paleocene (~95-58 Ma) turbidite complex in Southeast Alaska that is part of the Chugach and Prince William terranes (CPW). Dating detrital zircons allowed us to determine the time of deposition, the source of the sediment, and where it was deposited along the margin of the Cordillera. U/Pb dating was conducted on 33 detrital zircon samples from the Sitka Graywacke on Baranof, Chichagof, Yakobi Islands, and the southern part of the Fairweather Range. These data provide new insight into the maximum depositional age (MDA), stratigraphic framework, and source terrane evolution.The dating of the zircon reveals that the Sitka Graywacke consists of two stratigraphic elements: the young Sitka (~75- 58 Ma) and old Sitka (~81- 95 Ma). The old Sitka is dominated by nearly homogeneous detritus from an adjacent mid-Cretaceous arc complex built on a Jurassic basement. The primary population of zircons (P1) occurs at ~100 Ma, lesser populations in the Jurassic (150 and 195 Ma), and minor modes at ~350 Ma, ~440 Ma. The young Sitka is dominated by a heterogeneous volcano-plutonic complex built on several different basement terranes. Young Sitka has a primary population between ~78 to ~67 Ma and lesser modes at 180-190 Ma, ~340 Ma, ~420 Ma, a minor Precambrian (PC) population (2.7 %). The old Sitka may be a local facies that is part of Wrangellia and correlative with the western Gravina, which has a depositional contact and clear alliance with the Insular terrane (here Wrangellia and Alexander). The young Sitka may be a regional facies that is identical to the units of the CPW along the southern Alaskan margin, including the Valdez/Orca in Prince William Sound, the Kodiak Formation, and the Shumagin Formation. The young Sitka and and the units of the CPW are thought to have accreted to Wrangellia, suggesting that old Sitka and young Sitka are not allied. This study clarifies the stratigraphic relationship of these units and allows for a better understanding of translation along the margin of the Cordillera.