Abstract Intraplate volcanism within the Pacific Plate not generated at spreading plate margins is most obvious in Hawaii and the Hawaiian-Emperor volcanic chain. This chain forms a global relief feature of the first order. This chapter consists of five separate sections that summarize the volcanism and geology of Hawaii and the Hawaiian-Emperor chain. Less obvious but probably greater in overall volume are other seamounts and seamount chains scattered across the northern and eastern Pacific basin. Some of these appear to owe their origin to intraplate volcanism, but many probably formed at mid-ocean ridges. Batiza (this volume, Chapter 13) discusses these other, largely submarine, volcanoes. The Island of Hawaii lies at the southeastern end of the Hawaiian-Emperor volcanic chain—a dogleg ridge, largely submarine, stretching nearly 6,000 km across the north Pacific Ocean basin. From Hawaii the chain extends northwestward along the Hawaiian Ridge to a major bend beyond Kure Atoll. North of the bend the chain continues in a northward direction as the submarine ridge of the Emperor Seamounts. Volcanoes are active at the southeast end of the chain and become progressively older to the northwest, reaching ages of 75 to 80 million years at the north end of the Emperor Seamounts. Most of this volcanic chain, with an estimated area of 1,200,000 km 2 , lies beneath the ocean. Only the Hawaiian Islands and a few atolls of the Hawaiian Ridge, totaling some 16,878 km 2 , rise above the sea (Plate 5).

Nearly twenty flows of the Columbia River Basalt Group (CRBG) can be paleomagnetically and chemically correlated westward as far as 500 km from the Columbia Plateau in Washington, through the Columbia Gorge, to the Coast Range of Oregon and Washington. In the Coast Range near Cathlamet, Washington, the CRBG flow stratigraphy includes 10 flows of Grande Ronde Basalt (1 low-MgO R 2 flow, 6 low-MgO N 2 flows, 3 high-MgO N 2 flows), 2 flows of Wanapum Basalt (both flows of Sand Hollow from the Frenchman Springs Member), and the Pomona Member of the Saddle Mountains Basalt. Elsewhere in the Coast Range, additional Grande Ronde Basalt flows, including flows of Winterwater or Umtanum, and additional Wanapum flows, including the flows of Ginkgo, have been reported. Thus at least 18 to 20 CRBG flows reached the coast region. Several of these distal flows have distinctive chemical and magnetic characteristics that are shared by nearby isolated intrusions in Coast Range sedimentary rocks, thus strongly supporting recent suggestions that these intrusions are invasive bodies fed by CRBG flows. Magnetization directions from several flows indicate 16 to 30° of clockwise rotation of the coast with respect to the plateau since middle Miocene time.