Drill Core Correlation with Ground Penetrating Radar Profiles

Much of the data collected during the summer of the 1998 was tied to the drill core and vibracore records. GPR profiles were collected along all drill site locations where possible. For consistent GPR data collection 100 MHz antennae with a 1000 volt transmitter were used. Where interesting sedimentary structures existed, other antennae frequencies were utilized. The topographically corrected GPR lines imaged the upper 4-6 meters and allowed for correlation of GPR profiles with sedimentary packages revealed in the drill/vibra core. The drill cores also confirmed previous GPR interpretations (1996 and 1997) of paleo-scarps where augering and vibracoring could not penetrate. Figure 1 100 MHz GPR profile (W-E) shot in 1997 near Copalis River. Drilling confirmed placer location at 190 – 210 m and also investigated Pleistocene base seen at 4 m depth at east end of the profile (dipping westward). Figure 2 100 MHz GPR profile (W-E) shot in 1998 at Rossevelt Beach. Drilling confirmed shallow sand/beach deposit above a Pleistocene bench seen at ~ 1.5 m depth. Note the small channel like feature center on 10 m. Figure 3 100 MHz GPR profile (W-E) shot in 1996 and 1998 on the Camp Rilea Militar