Roman Catholic Diocese of Helena Roman Catholic Diocese of Helena The Diocese of Helena () is the Catholic diocese for western Montana with its cathedral located in Helena, the state capital. The diocese was erected from the year-old Vicarate of Montana on March 7, 1884, while Montana was still a territory. The diocese is a suffragan of the Archdiocese of Portland, which encompasses Oregon, Idaho, and Montana. Before becoming a diocese, this was the Vicariate of Montana (covering the whole territory and then state of Montana). For its first twenty years, the diocese served all of Montana. In 1904 the new Diocese of Great Falls-Billings
Geography of Saint Helena this is not the case on St Helena itself. St. Helena exists because of the St. Helena hotspot which began to produce basaltic lava about 145 million years ago when it was near the constructive plate margin of the Mid-Atlantic Ridge. The movement of the African Plate away from the hotspot has left the chain of the St. Helena seamounts, which may connect with the Cameroon Volcanic Line. St. Helena, the most south westerly point on the chain, is close to the plate margin, but the last volcanic eruptions occurred about 7 million years ago. The first investigations of St.