Figure 2--This image consists of colored, isostatic gravity values superimposed on grayscale, aeromagnetic total field values (from Finn et al., 1998). Scale at right is in milligals. High values (reds) are most commonly related to mafic rocks. White dashed lines are locations of magnetotelluric profiles. SFZ=Seattle fault zone;WIF=South Whidbey Island fault; LFZ='Legislature' fault zone; SHZ=St. Helens fault zone; WRZ=western Rainier zone; PHFZ=Portland Hills fault zone; OWL=Olympic-Wallowa lineament; DMF=Devils Mt. fault zone; DAR=Darrington fault zone; OLMT=Olympic Mt. thrust (informal to this report); LRT=Leech River thrust; SB=Seattle basin; EB=Everett basin; BB=Bellingham basin: GB=Grays Harbor basin; TB=Tacoma basin.