East of Crossville, the Crab Orchard Mountains, the southern fringe of the Cumberland Mountains, come into view as the road descends several hundred feet. At mile 329, the interstate enters Crab Orchard Gap and proceeds through a narrow valley once prone to rockslides. About later, I-40 has an interchange with US 70 near the town of Crab Orchard. Beyond this point, the Interstate descends into a short depression before crossing into Roane County and mile 340, entering the Eastern Time Zone. Shortly thereafter the road begins its descent of the Cumberland Plateau into the Tennessee Valley and the speed limit drops to 60 mph in the eastbound lanes. I-40 hugs the slopes of the plateau's Walden Ridge escarpment for several miles, containing what some describe as dramatic views of the Tennessee Valley below to the south, before reaching the base of the plateau at mile 347 between Harriman and Rockwood, and containing an interchange with US 27. As it enters the Ridge-and-Valley province of the Appalachians, of which the Tennessee Valley is a part, I-40 crosses a series of ridges and valleys characteristic of the region's topography. About later is an interchange with SR 29, and about later, the road crosses the Clinch River, with the Kingston Fossil Plant and its twin smokestacks dominating the view to the north. About later is an interchange with SR 58 southbound in Kingston, and at this point, I-40 begins a brief concurrency with SR 58. After ascending a short and relatively steep ridge out of the Clinch River Valley, SR 58 splits off to the north about later, heading towards Oak Ridge. Continuing through the relatively rugged terrain of the Great Appalachian Valley and crossing additional ridges, I-40 crosses into Loudon County about later and has an interchange with US 321/SR 95 near Lenoir city, before reaching I-75 about later.