Open-File Report O-08-07 Preliminary Geologic Map of the Dixie Mountain Quadrangle, Washington, Multnomah and Columbia Counties, Oregon. Publisher: DOGAMI The new geologic maps of the Linnton and Dixie Mountain quadrangles provided a view of the geology of the NW Tualatin Mountains (Portland Hills) that is unprecedented in its detail and scope. These two maps are the first 7.5 minute quadrangle geologic maps ever released by the Oregon Department of Geology and Mineral Industries that were prepared using state-of-the-art high resolution lidar technology (a 7.5 minute quadrangle map covers an area of about 49 square miles). CD-ROM Price: $ 10.00