The absence of significant thinning of Pliocene-Pleistocene strata across Stonewall Bank indicates that the anticline began to grow as recently as the late Pliocene or Pleistocene. Yeats et al. Shaded relief image of the late Miocene-early Pliocene unconformity structure contour map on the central and northern Oregon continental shelf. The western edge of the image represents the current extent of basinal sediments, although the basin may have extended farther west and since been eroded. The unconformity reaches the seafloor at the eastern edge of the shaded image, where middle Miocene and older formations are exposed.
Depths are below sea level.
Cross sections of the late Miocene-early Pliocene unconformity taken across the shaded relief image of Figure 5. The unconformity is at a maximum depth of 2500 m in the axis of the syncline, but uplifted and eroded at Stonewall Bank. B-B' crosses Heceta Bank, one of several prominent and recently uplifted submarine banks on the Oregon margin. C-C' crosses the northward extension of the Newport syncline and the Nehalem Bank fault. This fault uplifts and truncates the unconformity and projects into Netarts Bay where it deforms late Pleistocene sediments.