A geophysical study of the North Scappoose Creek, Alder Creek, Clatskanie River lineament, along the trend of the Portland Hills fault, Columbia County, Oregon

A seismic refraction study of a portion of the northeastern margin of the Tualatin Valley, Oregon

“…Schmela (1971) and Anderson (1978) studied the extension of the Portland Hills fault trend into the Clackamas River drainage. The trend of the Portland Hills fault to the northwest was examined by Haas (1983). (From Johnson, 1987).…”