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<br />303334 <br /> <br />series of earthflows. We encountered an ancient stream gravel between 210 and <br />215 ft below the surface which we interpreted as being associated with a <br />distributary channel on an older landslide surface. This supports the <br />multiple event hypothesis for formation of the Whiskey Creek earthflows. <br /> <br />The fourth EDM point at Whiskey Creek was installed expressly to monitor <br />surface movement, if any, associated with basal movement indicated by <br />inclinometer tilt. Not only does this offer the ability to measure movement <br />both at depth and at the surface and compare them simultaneously, but enables <br />the geologist to qualitatively predict whether large scale movement is by <br />flowage or translational landsliding, This is important because prediction of <br />the effects of a large-scale event depends in part on knowing the style of <br />movement. Ancient movement probably was by earth flowage but climate and <br />ground moisture conditions are probably different now than they were thousands <br />of years ago when the last major Whiskey Creek landslide event occurred. The <br />potential for reactivation will have to be evaluated as future instrumental <br />information is obtained. ' <br /> <br />In conclusion there is only a partially operational landslide monitoring <br />system installed at Whiskey Creek. The inclinometer hole will have to be <br />re-drilled if the program originally planned is to be effective. <br /> <br />( <br /> <br />In the future it would be wise to drill more exploratory holes and <br />possibly conduct a seismic reflection survey of the Whiskey Creek landslide, <br />especially in its lower part. If the massive earthflow hypothesis is correct. <br />the lower part of the Whiskey Creek landslide buries an ancient land surface <br />topography which may include the stream bed of the ancestral Eagle River. For <br />the 'purpose of determining relative' stability of this landslide material it is <br />essential to know the configuration of this surface, The west lobe of the <br />Whiskey Creek landslide toe currently appears stable whereas the east one is <br />not. This may simply be because the roadcuts are on the east side or perhaps <br />for some natural geologic reasons. In addition, material properties testing' <br />should be done on the landslide material that was cored to determine physical <br />properties, both undisturbed and remolded. <br /> <br />Dowds No.2 Landslide <br /> <br />... <br /> <br />Although not specifically assigned for study or instrumentation during <br />thi.s investigation.I .dicLsol!lefielclrecollnaisSllnce ofth!! ~rei!. <!uring_wpr:~on <br />the other landslides, I had also inspected the Dowds 2 landslide on two <br />previous occasions in the spring of 1982 and 1983, This landslide has caused <br />damage to the Interstate highway as recently as two years ago and has been <br />instrumented with EDM points by CDOH along the bin wall above U.S. Highway 24. <br /> <br />- 12 - <br />