There is no Fossil Hill. However there is Fossil Falls (as indicated by the above link). It is a little south of Olancha, and exactly half way between my house and my parents'
The hill you're talking about is Red Hill, where scoria/pumice is mined for various uses (including patching the asphalt on 395, you might've noticed red-colored sealant in that area). You can hike to the top of that hill, it's only about 300 vertical from the highway.
Probably the worst, roughest washboarded dirt road in the world will take you to a trailhead and a sign board. You walk through a couple washes lined with ancient lava flow maybe a half mile or so to the site of the falls, where the Owens River used to flow through and over the lava cliff. Loose rock carved out circular pits in the lava, some of them around enough and deep enough to stand in. Quite fascinating. I usually come back with a pocketfull of obsidian schards and colorful scoria.
Most people blow through Owens Valley out of boredom, I find everything between Little Lake and Bishop fascinating. An 11-hr drive home to San Diego usually ends up being a couple days instead.