Tower Fall results as Tower Creek plunges into the Yellowstone River and its canyon. The Creek flows over a cliff of volcanic rock from eruptions of Absoroka volcanics 50 million years ago. Just north of Tower Fall the road overlooks The Narrows of Yellowstone Canyon. The road construction has exposed a cliff with a spectacular layer of 2.2 million year old columnar basalt at road level. This volcanic flow overlies a thick layer of sedimentary conglomerate. Across the canyon the Yellowstone River has exposed rocks that provide a look back through time. The lower rock unit that makes up most of the height of the canyon is composed of coarse sands and gravels deposited by ancient glaciers and the Yellowstone River. Above that are two layers of approximately 1.4 million year old columnar basalt. Above the basalt are volcanic ash deposits from the Yellowstone caldera explosion 630, 000 years ago. Glacial sediments are at the surface.