CLARNO TUFFACEOUS BEDS
Some Clarno volcanoes erupted with great violence producing large clouds of fine-grained ash. As this ash fell to the ground it was washed into riverbeds and marshes, accumulating as multiple beds of tuffaceous mudstones, siltstones, and sandstones which are now obscurred by deeply weathered uniform clays covered by red and tan soils.
Where these deposits have been exposed, details of each layer are visible with well preserved fossil leaves, fragments of wood, and traces of seeds and nuts.
If the muddy ash came to rest while still within a forest (or jungle), entire tree trunks were sometimes preserved as charcoal.
When the ash reached lakes it was deposited in multiple beds of lacustrine tuff containing fish remains and diverse leaves of many different plants.
One locality near Mitchell has yielded over 150 distinct fossil species of Eocene fruit and seeds including walnuts, cherries, grapes, kiwis, palms and even bananas.
Near the Clarno type locality northwest of Mitchell, evidence has been found of an Eocene river channel in which many different species of land-based and water-dwelling animals were buried in tuffaceous mud.
Fossil bones representing rhinoceros, crocodilians, titanotheres, and many other Eocene animals have been recovered.
Traces of Eocene hot springs are suggested by deposits within Clarno bedded tuffs that display fiberous, concentric structures similar to textures in travertines.