Abstract: "Drill hole UCe-18 was successfully logged with the U.S. Geological Survey-La Coste Romberg borehole gravity meter to a depth of 6,488 feet. That density increases with depth is apparent in both the alluvium and volcanic rock. The in situ density of the alluvium measured by the gravity meter ranges from 1.77 to 2.34 gm/cc; the lake beds beneath the alluvium have a density of 2.22 gm/cc; and the rhyolitic rocks range in density from 2.26 to 2.47 gm/cc. The average density determined from the borehole gravity meter data for the alluvium plus the lake beds is 2.22 gm/cc and for the volcanic rocks is 2.35 gm/cc."