Valley of Ten Thousand Smokes The ash-filled valley covers a area. The ash can be up to deep. In places deep canyons have been cut by the River Lethe, allowing observers to see the ash flow strata. Since the ash has cooled, most of the fumaroles are now extinct and despite its name the valley is no longer filled with 'smoke' (i.e. steam). Vegetation still does not grow in the valley. The signs of volcanic activity are still visible on nearby hills. Katmai's most recent eruption was in 1927, but there have been non-eruptive events as recent as 2003. The Alaska Volcano Observatory still monitors
Places of interest in the Death Valley area is lithified alluvial sediment. Mosaic Canyon is a canyon in the north western mountain face of the valley which is named after a stream-derived breccia sediment with angular blocks of dolomite in a pebbly matrix. The entrance to Mosaic Canyon appears deceptively ordinary, but just a walk up the canyon narrows dramatically to a deep slot cut into the face of Tucki Mountain. Smooth, polished marble walls enclose the trail as it follows the canyon's sinuous curves. The canyon follows faults that formed when the rocky crust of the Death Valley region began stretching just a few million years ago.