This study contributes the first paleomagnetic data from dated Cretaceous units of the Coast Belt (51.3 ¿N, 123.8 ¿W) in which paleohorizontal bedding surfaces can be identified with certainty. We sampled 38 sites through a 1.5-km stratigraphic interval of Cenomanian Silverquick sedimentary strata and Cenomanian to Campanian Powell Creek volcanics in the Tatlow syncline in the Tyaughton-Methow Basin. Magnetizations at 21 sites have high unblocking temperatures (TUB) and pass the tilt test (precision k=5 before untilting, maximum k=48 after 100% untilting). Magnetic minerals of volcanics show original textures, mean declinations in volcanic and sedimentary rocks are statistically identical, and polarity is consistently normal. The mean inclination (55.4¿¿3.4¿, probability P=0.05) of this pretilting magnetization is 20.1¿¿4.0¿ shallower than that excepted if the rocks were deposited in their present position relative to cratonic North America. Field and laboratory observations rule out other causes for these anomalous shallow inclinations. These rocks therefore have been displaced northward by 3000¿500 km relative to cratonic North America since mid-Cretaceous time. This displacement is almost 3 times greater than that estimated from mid-Cretaceous volcanics in the now-adjacent Intermontane Belt. Evidently the two belts were not amalgamated until latest Cretaceous or Early Tertiary time. These results are inconsistent with all previous geologically based tectonic reconstructions of the Cordillera. Magnetizations at eight sites in Silverquick and Powell Creek beds have low TUB and directional characteristics similar to those in three younger diorite intrusions. Reversed and normal polarities occur, the rocks are commonly highly altered, and maximum precision occurs after 40% untilting. The magnetizations therefore are interpreted as overprints of latest Cretaceous age acquired during folding. ¿ American Geophysical Union 1995